The updated Google Mobile App for Blackberry now has the ability to conduct a voice search. If you have a Blackberry and want to download the app, browse to http://m.google.com on your device.
The voice feature is available for Blackberry devices with O/S 4.2 and higher (except the Storm). The app without voice is available for devices with O/S 4.1+. The app for Blackberry Storm is not available yet - but they're working on it.