What I expect from start:
Basics:
gmenu2x type shell, probably with a terminal built in somewhere. Not a full fledged linux distro yet.
Solid emulators for the classics: snes, nes, mega drive (genesis to the US folk), etc etc (fairly rapidly I imagine people would port over the remaining gp2x emulators)
Hopefully a reasonable psx emu, dosbox and amiga emulation.
I suspect all the above are fairly likely.
Apps:
Basic text editor.
Media player (surely someone has done a mplayer port) possibly with an ugly as sin gui.
Photo viewer.
An mp3, ogg player.
A web browser (even if it is just dillo)
Hopefully an email app.
What I would like to see added shortly after:
Dreams:
A decent ebook reader, how about
fbreader?
Imrpoved apps (firefox, decent email client etc)
All the missing emulators.
A specialist
kittenwar app.
An excuse generator when I explain to my wife why two hundred odd quid is missing from the bank account.
Ports of classic opensource games.
Homebrew browser like on the Wii
I just hope I get to reporder before the wife finds out I stole her credit card ....