I'd say the best option here is to work with Canonical to make Ubuntu a stable gaming platform. Valve has the gaming expertise and Canonical has the Linux expertise and community mindshare, so I could definitely see them working it out.
That's a pretty interesting angle. But it might be a bridge too far. Gamers would almost certainly follow Valve to Linux. But asking them to give up their mp3 players, chat programs and background tasks while they're gaming?
Only if it were a living room solution, which has its own "day 1" sorts of challenges. (e.g. the number of titles with not only gamepad support, but where you truly do not need the keyboard/mouse to play.)
Wat.
Linux programs like Pidgin have support for almost all IM protocols known to man, it can handle any Portable Media Player with sane behavior (read: identifies as removable storage, which pretty much all players except the shitty Apple ones do) and last time I checked, Linux is capable of multitasking, too.
Managing your music collection as a distinct set of files and folders is a rather 90's concept. What matters is how the files are presented to the end user - they can be all slapped into a single folder and given GUID names as long as the resultant database presents them in a clear and meaningful way.
(Only partly kidding - I think your criterion for a "shitty" music player will find a great deal of dissent :3)
>Linux programs like Pidgin have support for almost all IM protocols known to man
Weak support. Anything beyond simple chatting almost universally doesn't work. File transfers, picture syncing, god forbid voice and video chat.
As for the IM protocols, maybe this will prompt people to migrate to better protocols like XMPP. ICQ, MSN, AIM and all those other proprietary protocols with their ad-laden, bloated clients (which I classify as nothing short of malware) should have died years ago.
So the current (in)existence of other Linux software would be irrelevant.
The proprietary NVIDIA drivers for Linux are built directly from the same source base as the Windows drivers, the only difference being the interface layer between the kernel and the driver. Feature set and performance are identical to the Windows drivers.
I'm not aware of any known critical bugs in the kernel parts. Usually when stuff breaks in the NVidia drivers, it's because of a combination of a kernel update and sloppy package management by the distribution. None of this should be an issue if Valve decides to release some kind of Linux based 'Steam loader' that boots directly to the game itself, or make their own Linux distro with tight control over the kernel and GPU drivers.
I'm not sure how good the ATI linux drivers are these days though.