If you take into account the small screen estate you have on a mobile device, e.g. custom apps instead of the social networks' (Facebook, Myspace, whatever) do make sense IMHO. Although I prefer the N900's browser over Mobile Safari on the iPhone/iPod Touch it's much easier to read and post stuff via the facebook app on my iPod Touch than via the Facebook web page on the N900. The page was designed for a much larger screen.
But the app angle is something we can change as a community, right ? And then again, custom apps can make use of the specific hardware features and that is something the good iPhone apps do. Considering the possibilities the N900 and Maemo5/6 offer, the vitality of the community and the lack of Apple like AppStore politics, there are certainly some very cool and interesting things ahead of us.