The interesting question to ask in this connection is not how many percent of Windows users are gamers, but how many percent of gamers are Windows users. I'll bet it's still 85-90%, if not more.

Wow. Sounds as though you are taking this personally, Wizball. Does someone have a little Mac envy? :P
I can put your concerns in perspective: that 4.87% represents about 30, 000, 000 users. But wouldn't it be a time consuming expense to port the games over to another platform? No, dosbox.conf is the exact same file on a Mac as it is in Windows. It just needs to be wrapped up with the game in a generic application package. Really, it's that simple? Yes.
A realistic hurdle I can imagine would be licensing. Contracts may have to be redrafted. Realistically, I don't see GOG branching out while still in beta, though it is a market they will want a piece of when they are big enough. Maybe you will even have that Mac of your own by then. Keep the dream alive, Wizball. :D

As a Mac user, and someone who has bought a few GOG games to run on my Mac, I felt I should respond to this. Yes, absolutely PC users come to Mac software forums and whine that their software isn't Windows compatible. All the time. And it's just as annoying.
That being said, I do think it would be reasonably easy to repackage the DOSBox games and sell them on Mac, at least from a technical standpoint. I've never had to reconfigure any DOS games to get them to work. In fact, the only challenge has been that I couldn't extract the game from the Windows installer, without having to use either Windows or WINE. I can understand if licensing prevents this, but it really wouldn't be difficult otherwise.
As for the rest of the games, while some of them do work in WINE (or more specifically CrossOver Games), until someone comes up with a good CrossOver Wrapper, I can't imagine selling them. For example, I got Heroes of Might and Magic III to work perfectly, but Fallout has been practically unplayable through it. There would need to be different version of WINE wrappers for different games, as regressions are common, and supporting updates to Mac OS might be difficult, as WINE is finicky. Unless GOG wants to work out an agreement with CodeWeavers, I can't see it happening.

I can safely say I do not. I have exactly zero interest in the Mac platform, as well as all the overpriced iCrap floating around. (Understand, I'm not actively trying to insult anyone who happens to like Apple's products. I don't feel like that about the people using them, just about the products themselves).
Really, it's that simple? No.
Yes, dosbox.conf is the same file. Is the exact configuration that works optimally on XP and Vista necessarily the same as the one that works optimally in Mac OS? No. Will it need to undergo just as rigorous testing as the Windows version? Yes. Does it need a completely different kind of installer? Yes. Does that need to be tested? Yes. Will the whole thing need to be supported afterwards? Yes. Will the Mac versions have exactly the same issues as the Windows versions? No.
Maybe I won't. Strike that, I definitely won't.
As you say yourself, the legal issues come on top of all the other stuff, and may be even more insurmountable. Is it possible that GOG will make Mac versions of some games someday? Certainly. But I wouldn't hold my breath if I were you. Instead, I'd go talk to someone who are already in the business of selling Mac games. I think you'd have a lot more luck with that, and a lot sooner too.

Mac users aren't playing those either, because none of them are compatible with newer versions of OS X and/or Intel Macs (unless you use a source port or whatever, but those are inevitably available for Windows/Linux/etc. too). What you're looking for is [url=http://en.wikipedia.org/wiki/Category:Mac_OS_X-only_games]Category:Mac OS X-only games[/url], which is a lot less impressive.

What games run just as well? The Unreal Series, IDs stuff and Blizzard Games? And I've never had rogue install files destabilizing my entire system, nor have I had games that I install try to run malicious code. I've never really heard of stuff like that aside from DRM tinfoil hat theories. Then again, I pay for my games. I have heard of Apple's updates destroying entire photo and music libraries for no discernible reason. I'm not a mac hater, in fact I look to get one when I get the money to have another laptop, but I'm not gonna buy into this whole lie that it does everything better than a Windows-based PC. I'd be buying it for the things it does different.

- A.K.A. I know :-)

I will just say two things before I quit because I really didn't come here to argue.
1. First hand experience reveals that the DOS games sold by GOG are 100% identical when run in DOSBox compiled for OS X. All I am suggesting is that if I can get GOG games running flawlessly within minutes, GOG can surely get their own games running flawlessly within minutes. That is why I believe compatibility is not a hurdle for possible OS X distribution.
2. One of my initial comments was that I am not holding my breath (in those words even.) I also said there are suitable solutions in lieu of official support. I don't understand why you seem to feel threatened by that. I will not say anymore (not because it is strangely offensive to some but because there really isn't anymore to say.) At ease, Wizball.

Install Fallout in a win98 bottle. Works perfectly.

Listen Tetris, I never said it would be awfully difficult to get it to work. All I said was that you can't be 100% certain that the same configuration will work equally well on two different platforms. But that is the least of your troubles. You still need to test it every bit as rigorously as the Windows version, because when a customer has an issue with your software, then "we dont know, we didn't test it" is NOT an acceptable answer.
Look Tetris, I feel threatened by it because GOG is still young, and I want them to succeed. Therefore I do not want them to go into areas likely to lose them money. I would also like them to spend their time making new PC releases, rather than spending time making old releases Mac compatible.
Also, I am tired of people who want to play games, but go out and buy a system wholly unsuited for that purpose, and then expects someone else to magically fix that for them.
Now, since you argue yourself that, given the game files, it's not really very difficult to get a DOS game running in DOSBox yourself, you might consider lobbying for a different approach. Many people (including myself, I might add) have expressed a desire for the DOSBox and ScummVM games to have an extra download option: a simple zip file with just the game files in it. That would eradicate the need for platform specific installers, whilst giving people with other platforms access to the game files without jumping through hoops to get them extracted from the Windows installer. It would mean a minimum of work for GOG, with benefits for the maximum number of users.
Does that make sense, Tetris?

I'll have to try that when I get home. Thanks!

I would like to see that. I backup the DOS files after installation to save myself the trouble should I need to reinstall. But I have a funny feeling that would be more of a tech support headache for GOG than OS X packages. Anyway, in the future, please read my comments carefully and don't project your unrelated anger at me: it is quite unbecoming.
EDIT: There is one more thing I should probably mention. Personally, I am not terribly interested in Windows games getting the royal OS X treatment. I doubt I would notice improved performance and I really like having my games sandboxed. I'm just suggesting GOG will probably want a piece of that market when they are ready to expand.

What? I was mimicking your style exactly.

Well, I meant the seemingly misplaced hostility. Regardless, I'm not angry. I am also just playin' around. It was a pretty good imitation, Wizball.

I agree with this bit I quoted. Even if the zipped up data files aren't for Mac/Linux use specifically, it's even more "DRM Free" I guess you could say. The installer isn't really DRM (unless you don't use Windows), but it's nice not to be forced to use it. Like with Duke Nukem 3D, some people just might want the .grp file to use with eduke32 and they don't need to run the entire installer.
I've also found the obligatory Adobe reader install intrusive. I have to sit there and watch the game install just so I can cancel the Adobe install immediately.