iPhone Dev Team has released redsn0w 0.9.9b6 software update for iPhone 3GS owners running baseband 06.15 which now fixes location services issue. To eliminate the network crash problem when using location services in iOS5, you must install the update immediately.
You can re-run this redsn0w update over an existing jailbroken iPhone 3GS at iOS5. Just choose “Jailbreak” again and de-select Cydia (Uncheck all the checkboxes). In case your iPhone 3GS have an old-bootrom, pre-select the IPSW first, since the tool cannot detect the firmware version automatically.
Users who are running sn0wbreeze can also run redsnow beta 6 to fix location services. It can be applied if you’ve hactivated with redsn0w (so worst case: Deactivate with redsn0w, then run redsn0w again to hactivate). It is important to note that by location services it doesn’t mean that the GPS issue for 3GS users on BB 6.15 is fixed.