Actually the Dell streak also uses an 800x480 screen, so theoretically it could only use up half a home screen like on the device shown.

In any case this isn't going to come to the N900 any time soon, if at all, Facebook has shown very little interest in smaller communities. Even the Winmo 6.5 community which is many times larger than ours has a very bad facebook application, and it can't be ported because it's proprietary software.

If you want better facebook integration without switching devices your best bet is to wait for Meego, which will probably have at least a little more than a lame scrolling widget.