Interesting. For the Nokia N900 there is Maemo Leste which also uses mainline Linux (+ a few patches they are working to mainline) and there everything works. Mind that works means in this case: Does what I want if I issue a number of console commands. However most of it by now even works via the GUI.

Keep in mind that Leste is a project by a few enthusiasts and writing drivers for undocumented hardware is a monumental task, writing GUI for a whole mobile OS is also complicated. So it is utterly astonishing, how far they got!