I tweaked my cell phone location-reporting midlet today (Friday). One funny thing is how my particular cell platform/provider sends two User_Agent defs when there's a post, which kind of threw me off for a bit. Had to check the HTTP server logs to see what was happening, but all was really well, since the target executable never failed and did its thing properly. J2ME is indeed more limited than its more capable, hardware-happy brethren, but there's always a way :)
For the server-side scripts, I modded what used to be handled by a cron job to now be handled at the end of the post target's script at run-time. So essentially an entity can report location on a regular basis, and the correct data will be ready for any queries related to location visualization. OK for a few users, but won't scale much, and this is not a concern at the moment ;)
When I have time to further define the map output, will post some pics!