While Google’s official Voice app has been banned by Apple (and is pending investigation by FCC), another Google Voice app ‘GV voice’ has made it to Cydia. Incidentally even GV Voice was banned from the AppStore along with the Google App.
At the same time, Google is also working on a web based version of Google Voice app that will eliminate the need approval from Apple to run on the iPhone. For now check out GV Voice on Cydia and do let us know if it works for you 🙂