Cingular decided to be B@$$tards with the latest AT&T/Cingular 8100 OS. They hide BBMaps in an effort to get you to pay for TeleNav. But you can beat them... All you have to do is search the LBS.alx file with a text editor for the exclude tag and remove the vendor ID of 102. Save the LBS.alx file and reconnect the 8100 to Desktop Manager.
While you're in there, you can also 86 the PTT crap if you don't use it. Similar process in the Platform.alx file. FYI, this was covered in another thread here: BlackBerry Maps - Where did it go?