now that n900 contains 32 gigs of space, it shouldn't be that problem to install the cups afterall, right?

The browser is gecko-based, so it could probably extended quite easily - provided that sources are available; don't know about that right now (but there's fennec coming).... some webkit browser woulb surely be trivial to implement (with the qt support built-in)

Add to that ghostview and openoffice port, and we're good to go with network printing - right (or even usb printing, if usb-host turned out possible)?

The real question here therefore is probably not whether it's possible (with n900+/maemo), but whether it's worth the effort - when advanced users will print just fine by the mentioned scp-copy+remote-print method, and regular users will be just hape they are able to watch movies and webmail...