Apple controversially kicked GV Mobile out of the App Store earlier this year citing that Google Voice App would confuse users (Whereas Skype and Vonage wouldn't?) who were using the phone.app. Sean Kovacs, the developer of GV Mobile, wasn't deterred. Within hours, he moved his app to the Cydia (Jailbreak) store where it has enjoyed some measure of success and has seen regular updates.
Those of us who downloaded the 'legit' GVMobile before Apple removed it, aren't able to use it anymore because Google has updated their service.
Kovacs is hoping Apple will change its tune, however and is submitting an upgraded version 2.0 of the GV Mobile App to the App Store.