Fring has updated its iPhone application for two-way video calling on the new iPhone 4. Although Fring iPhone app already has support for video calling but this time it includes two way video calling with the iPhone 4 front camera as well.
You may grab the latest Fring app via following iTunes link and it works for iPhone and iPod Touch.
Download Fring for iPhone
Watch out the following video demonstration of Fring on iPhone 4.