Yahoo + Linksys = VoIP cellphone?

According to this Yahoo article, Linksys and them have teamed up to make a cellphone that uses Voice Over IP to allow for far cheaper mobile phone services. The article doesn't go into the details about how this would work (what cell towers could they use? CDMA or TDMA? what is the airspeed velocity of a unladen swallow?) or how much it would cost per month or per call. The phone itself (obviously not pictured here) would cost about $100.

Could this be the start of cell service revolution? I would want to try it, I already pay far too much for my cell service now.