Google Voice on the iPhone has been MIA since July of 2009, when the official Google Voice application and two other supported apps were removed from the App Store. Apple has now released more specific guidelines on what would be rejected from the App Store which may have opened a window of re-entry of Google Voice into iPhoneLand.
Sean Kovacs, the developer of one of the previously removed apps GV Mobile, has applied for his app's reinstatement into the App Store since it does not seem to violate any of Apple's guidelines. Apple responded that he was welcome to reapply, which was encouraging considering that attempts before had only been met with silence. Kovacs received world from Apple that "it will most likely get back in," but nothing's ever for sure until you see it in the App Store.