770 owners followed by n8x0 owners know this well. Two things make the situation a bit better. The first is Qt, more specifically QtMobility as it abstracts a lot of the device specific bits. There are still items not covered by QtMobility and items that are only available in new Qt. The second is the Community OBS which will (eventually) allow building applications for Maemo 5, Meego-Harmattan, and Meego. It'd be nice if they add Maemo 4.1 to the OBS so devs have a one stop shop for all platforms.

At that point the main challenge for developers is testing. This'll be a problem for me as my device is a Nokia loaner and once they take it away things will be a bit more difficult to support Maemo 5.