that's not entirely true - if usb host was supported, there are USB video cards available, supporting SVGA etc. - sure, you can't play video thru them (because of the usb overhead), but if there is a linux driver, it would work.

even if direct video out in resolution >800x480 isn't available, it still should be possible to use ssh to forward X apps and start applications on n900, and have their windows placed on other desktop (i.e. access a kind of remote-desktop)... this of course isn't too convenient, but the following scenario should be easily doable:

* bring N900 to presentation, with own data...
* connect from (e.g.) linux desktop machine to n900 (thru wifi + ssh)
* start document/presentation viewer/browser/whatever on n900, the window shows on the desktop machine (even one of size 1600x1200 shouldn't be a problem)

this is a little clumsy example, but similar and more useful usages might be found...

however the truth is that n900 might not be powerful enough to enable convenient office work (e.g. opening more than a few browser windows, document editors etc.)...