Same problem here (using .141 on AT&T). I've downloaded and installed the icon file, but every time I've done a battery pull, or even just power the phone off and on, the BB Maps icon disappears again. I've done the download/install several times and decided to give up. I'm just using Google Maps at this point.
If you lose it, in a pinch I send my location in bbm and it brings up an option where you can view your location. When you click view, it brings you into bbmaps. Dirty solution, but it works.
For some reason I can't get the link to paste properly. Do a Forum Search for "BB Maps launcher for AT&T". It's in the Blackberry Native Apps subforum. The first post has a link to download the app. I went to the link using my phone's browser.