Parasitius: Lucasarts and *spit* EA are hardly going to share any potential monetary windfall with a 3rd party site like GoG as they are just too damn greedy. They will no doubt have people keeping an eye on how things go here and see just how popular the site becomes and how much income it's liable to make, and then promptly decide to do their own version of the website to keep 100% of the profit to themselves.
QFT. Publishers have noticed that services like Steam work, but the really major publishers aren't going to try selling through an established distribution system first, they're going to try their hand at setting up a similar system themselves. Why outsource *making money*, right? That's just stupid. If people want to download our games, we'll make them available ourselves and cut out the middle man! How hard could it be?
Gamers can expect nothing but to get shafted in these setups, since publishers are short-sighted and will focus on the bottom line before coming anywhere near to giving you a good gaming experience. They're going to be peddling the same DRM-protected crap at the same price as you'd pay in the store, but without a box or a disc or a way to get a refund. A great deal -- for the publisher, that is.
Old games have it better, since they either never had DRM or they had DRM that's hopelessly outdated and ineffective now, and selling them as new physical copies is no longer worthwhile so there's no threat to the brick and mortar stores. Then there's the fact that the market for these games is smaller, which automatically cuts down on the piracy *if* the games are easily available legally, since they're harder to find for download (and for most people it's a no-brainer to pay for easy access to games you know are good *and* cheap). GOG is a good business model because they've got a relatively easy sell for publishers: "for a pittance we can market the stuff that could be making easy money for you and is just not doing anything now, what have you got to lose?"
Still, keep in mind that for the really big guys it actually looks like more trouble than it's worth to make old stuff available. It's much easier to crap out cookie-cutter new releases through the existing process and make a few megabucks from all the 13-year olds hungering for the latest new thing than it is to dig up the ancient catalogue, sort out the rights, polish the games up for the new generation of hardware and set up distribution all to satisfy the few thousand people who might be interested in a copy. Maybe it could make good money, but why risk it? Just because the customers want it doesn't mean they have to sell it, and having a monopoly through copyright means there's no rush.