Stellarium Mobile has a few additional modules, including a GUI specifically tailored for a small screen and support for the N900's GPS and accelerometer. The problem is that the developer was hoping to get some money from it in Nokia's Ovi application store. He thought that leaving it licensed under the GPL wouldn't work for a commercial application, so he asked for an exception from the rest of the developers. Not all agreed, so at the moment the project hasn't been released. I don't know what Fabien is going to do eventually. (Oh, and he is the lead developer, which is a bit awkward.)