Truphone updated their free VoIP/IM iPhone app claiming…
Truphone 3.0. Our best app ever!
Truphone says they’ve enhanced voice quality while simplifying instant messaging with a variety of services. It can be used for voice chats with users on Skype and Google Talk as well as other Truphone users. Unlike Skype, VoIP calls can be used when on 3G as well as WiFi.
Note that there is a different version for use with the second generation iPod touch.