Back in July of 2009 Apple formally removed and banned all apps that worked with the Google Voice VOIP solution. Google Voice is a fully functioning VOIP program providing its users with their own local phone number. There was some speculation as to why Apple would not allow iPhone users to use Google Voice from their handset but Sean Kovacs (an app developer) recently tweeted that he has assurnace from Apple that his next version of the Google Voice app will be accepted after he makes the requested changes.
This would be a great productivity tool for iPhone user. If he is successful at getting him app into the app store we will be back with more information about the program and how to utilize it with your iPhone.