Yup, that is an issue with most AOSP builds.  The fix is a bit of a headscratcher (meaning don't know why it works) but here's what you need to do.  
1) Backup your AOSP version.  
2) Wipe data etc, and install one of the sense roms  (bamf or whatever and don't worry about reloading all your data, cause you won't need it for this process).  
4) Once you load the sense rom, activate maps, get a gps lock then 
5) Reboot to recovery and load your AOSP backup.  
 
Voila.  As I said, i don't know why it works but it does.  Then do another backup and you will always have a backup with working GPS.  I would also download GPS Status from the market.  It is a great app.