I was looking for a simple possibility to upload my GPX Tracks to the Openstreetmap Database. One solution is to use the Webfrontend but month ago I developed my own small application to store (or create new) tracks, put them as overlay on Mapnik or Osmarender map, remove unnecessary waypoints and export the tracks again to GPX to use them again on my GPS device.
This weekend I tried to develop my own client for uploading my GPX Tracks. I think the exported GPX track should be ok, because I tried to upload by the webfrontend to the public dev server and my track was accepted but when I try to use the API I just got a 500 error back from the server. I posted the HTTP header and the GPX Track I am sending to the server at http://forum.openstreetmap.org/viewtopic.php?id=9306. Maybe someone can resolve my problem.