The Google Voice app for BlackBerry has been updated version 0.2.0.2 (what a fun version number!). An update for the app has been long overdue, and this version includes an option to check your balance, faster dialing and banner notifications.
I've been hoping that all of the Google apps for BlackBerry (Google Voice, Gmail app etc.) would step it up at some point and flow better on BlackBerry, but it really doesn't look like that will happen anytime soon. If you're a Google Voice user head to the link below from your device to download.