My list is short becuase the n800 totally rocks as it is.

A2DP
USB Charging
Maybe 1024x600 res, but only depending on the next two wishes
Graphic Acceleration in hardware (drivers)
3D
Bluetooth Mouse profile.
OpenGL
OpenAL


For software features, I'd really like to see:
Autodownloading of RSS Video Streams (get up and watch the CNN feed each day)
Office Suite
Native Support of most codecs. Meaning; instead of the user having to cobble in ogg and mplayer etc.... this should ship with broad codec support.
Media Box should be default media player
Ability to designate handler apps for media. (Mp3 to Canola, AVI to Media Box, etc...)
Syntax highlighting code editor


Can bluetooth support a keyboard, mouse, headphones and a datalink, all at the same time?

I like the pause/answer button on the headphones, BUT the audio quality sucks. Need a way to add better headphones and keep the features.