Are other applications also able to start the GPS? The problem with maemo mapper is that it supports a bunch of ways to start the GPS. This is due to the fact that maemo mapper already supported GPS devices before os2008 introduced the GPS framework.

Maybe you didn't configure the GPS properly for the GPS framework but instead only configured it inside maemo-mapper? Can you e.g. access the GPS from the control panels GPS entry? Can you update your "home position" there (i am guessing the exact wording as my n810 talks german)? If your GPS only works inside maemo-mapper, chances are that you didn't properly setup the GPS in the os2008 GPS framework.

Under os2008 you basically don't configure anyting GPS related in maemo-mapper. You especially don't set a specific bluetooth gps but just leave everything blank and let the GPS framework do its thing.