It's been a while waiting to be approved but now Apple and Google have agreed to add the Google Voice for iPhone App  to the Apple App Store.

Google Voice lets users make cheap phone calls from their iPhone. Incoming calls work normally via the callers mobile provider with no extra cost. Outgoing calls are transferred to Google's VOIP ( Voice Over IP ) servers so that calls become cheaper. VOIP is not popular with mobile operators as they lose out on revenue.

The newly approved Google Voice for iPhone App  offers cheap rates for international calls, free text messaging to U.S. numbers, Voicemail transcription and will display your Google Voice number as caller ID when making calls.

Specific features for Google Voice on the iPhone are with push notifications, the app will alert you instantly when you receive a new voicemail or text message and most of your calls will be placed via Direct Access Numbers, making them connect just as quickly as regular phone calls

The direct link to download Google Voice for iPhone App  is here but please note that this is only available in the US at the moment and you need an iPhone with iOS 3.1 and also a Google Voice account. As soon as the App becomes available in the UK we will post this at 3G.