This Line2 app was just approved after a 3 month delay, partially caused by the Google Voice shenanigans Apple pulled back in July when they pulled out all the Google Voice apps from the App Store. This is really similar.
According to GV Mobile developer Sean Kovacs, an iTunes Store support representative claims that Apple removed the app following an AT&T request. Identified as Raymond C. in the chat screenshot, he apologized for "this unfortunate removal of a great application."
Apple may have booted the official Google Voice App and GV Mobile from the app store, but the developer of GV Mobile would rather give it away for free on jailbroken phones then see his work go to waste.