I also had the problem, that Blackberry Maps was unavailible on a 8310
Tried to use the Download from Rim.
BB Maps did work, but GPS stopped working completely.
Zeroed the device and again loaded the OS. GPS again is ok, but no BB-Maps.
google, Nav4All etc. etc. are running fine.
on a 8800 BB-Maps and GPS is working fine - same OS version.
Looks like I have to wait until its finished or is there a fix for this ?