Are there any plans, or ideas being thrown around between GOG team members to add more features to the GOG downloader, perhaps have it more like a Steam-type thing? Game collections could be neatly managed, as they are on the website, etc.

Beware the slippery slope that is Steam. I'm not opposed to expanding the functionality of the downloader, but one aspect must hold true always: It must not be mandatory!

Agreed, while I use Steam a fair bit, there are many aspects about it which annoy me, especially the mandatory nature of it.

All I want to see is for games with multiple parts to allow each part downloaded individually, rather as a single download entry (of all parts).
The GOGdownloader and the Steam Client are slightly different in their aim. While possible, I think it's a little unneeded unless functionality expands to more than just a list of games.
As with (some of) the others though: make it optional.

I hope not. All I want in the Downloader is for it to not be AIR-based.

I hope not too, but about AIR-based downloader - what's wrong with it?

AIR is a developer nightmare. Can you imagine having to recode programs and making everything look Flash-like?

Don't know about that. Adobe Reader and Adobe Flash have always worked well for me. Also, my friend who works in the video department of our church swears by After Effects.

I kind of like it - I'm not a programmer and know nothing if Java or C++, but with my skills in HTML, CSS and Javascript I can still develop locally running applications with save/load functionality that my subjects - eh, friends, I mean - can use without always being connected to the 'net. (I don't know flash/flex either, and I don't need it to develop AIR applications).
What about having to recode programs to look flash-like?
What in the nine hells is a "flash-like" look? You mean to say that applications coded in flash/flex are bound by a specific set of graphical rules? I'd say that's fully up to the designer of the application, a good craftsman doesn't blame his tools, he learns to use them (yes, I know that might sound like a personal attack).
Developer nightmare?
Those of you that don't want to develop in AIR are by no means forced to - you can still code in Java, C, C++, C#, Python, Visual Basic, COBOL, Delphi, Fortran, whateversuitsyourfancy, or any other language. HTML, CSS, Javascript, and even Flash/Flex are good enough tools for us that do not know real programming languages.

Based on what has been said in the past about the plans for GOG, this will not be happening. It has always been intended that the website would act as the "front end" for your GOG games collection and that there would be no additional applications required to install or use those games. If you want that kind of functionality, then just add your GOG games to Steam as a non-Steam game.

Yes I can imagine, but I don't really get a point since AFAIR downloader is AIR-based since its began.

No more features needed, downloader needs to other way of downloading games - nothing more imo.

Adding an option that will shutdown your PC when a download has been completed would be very handy in my opinion, saving electricity is always good.