The new beta release of Beyond411 now supports GPS based search-- for example, you can do yellow page searches and get driving directions from your current location, wherever you are.
You can install the 4.20 beta release over-the-air from
http://thebogles.com/beta/b411.jad.
This is a beta release and you may encounter bumps in the road, please let me know of any issues.
Of course GPS functionality is only enabled on Blackberries that support GPS, e.g. the 8800 series. To turn on GPS search mode, select GPS from the location drop down at the top right of the search screen.
Thanks to geonames.org for a reverse geocoding web service licensed under a Creative Commons Attribution 3.0 License.