A new mobile-phone MVNO carrier, Zer01 Mobile announced that it will give you 100% unlimited voice and data on smart phones for as little as $69.95/month, without a contract, and on a broad nationwide network
Update: (they're not a MVNO as I originally reported due to information I read on the web)
Unlike MVNO's which have agreements with a carrier to resale the carrier's service, ZER01 has no such agreement in place with any carrier, and in fact, actually provide their own voice and data to you.
Zer01 Mobile will even offer unlimited international calling (to 40 countries) for an additional $10/month. How are they able to offer such inexpensive calling? Take one guess. Yep, they're using VoIP. The company will use a VoIP application for routing of all calls. Unfortunately, currently that app only works on Windows Mobile - sorry Apple iPhone fans (& Blackberry).
Update - However, Zer01 has plans to make this service available for users of Blackberry, Palm, Symbian, and other hand set devices in the near future.
According to PC Magazine, "Zero01 has some sort of quality-of-service mojo that lets VOIP run even over slow EDGE and GPRS networks."
Zer01 works with unlocked Windows Mobile phones that can run their application, but Zer01 also plan to sell three HTC phones, the TyTnII (AT&T calls it the Tilt), the Touch Diamond and the Touch 3G.
It'll be interesting to see if people are willing to try 100% VoIP mobile phones. Will they trust the voice quality and coverage area? Then again, it is AT&T's nation-wide coverage area, and cellular voice quality isn't that great either. So users might be willing to take a chance. Certainly the price is very attractive, and with no contract requirement, customers might be willing to give it a shot.