Maybe Zune Phone is not exactly what the latest rumors from CrunchGear were talking about. Maybe we are talking about a new device which works in the TV band using the cognitive radio idea to do something. Microsoft cooperates with Dell, Google, Hewlett-Packard, Intel and Philips on this. According to this document its use will be consumer broadband access and networking...
The FCC filing mentioned in the previous days contains some answers from Microsoft about a prototype device to be tested.
The concept of cognitive radio is used on a device when it wants to verify there are no other transmissions in the band/channel which could interfere with it. The system actively monitors the band and when an a transmission is found it changes to another. The prototype device described here has to do with Digital TV and Wireless modems.
It will be able to tune to TV channels 2-51 using a 4.5 MHz signal bandwidth and will sense Digital TV broadcasts, microphones and try to sense other incumbent signals. If a signal is detected the device switches to a vacant channel.
It looks like it has nothing to do with a phone, but in the future of protocols like WiMAX a phone can be much more than today.
Read the FCC document by yourselves and write about what you think the use of such a device could be.
Read more about Cognitive Radio on Wikipedia