Maemo Mapper doesn't support the wpt tag. It's a long story, but it doesn't really fit with Maemo Mapper's track data structures. (Why are the waypoints separate from track points? How am I supposed to correlate the two?)

Maemo Mapper only supports the trk tag. The trk tag in your example should actually cause a three-point track to be imported into Maemo Mapper (as a track or a route, depending on how you open it). To create waypoints, a given trkpt object should have a desc tag inside it, the contents of which determine the text that is displayed (or read by flite) when you approach the waypoint.

I've been meaning to add more robust support for GPX to Maemo Mapper, including support of the wpt tag, but it might break backward compatibility, so I'm saving it for Maemo Mapper v2.0.