It's almost 100% confirmed that the Zune phone is coming. Crunchgear had a tip this morning that says Microsoft execs are working out the details of the device today, and are planning the date which the Zune Phone will be released.
UPDATE: Looks like sources at Crunchgear were wrong.
Our own tipster confirms this. He says that it probably will NOT be running Windows Mobile (thank god), and is on track to be released late this year. It will be compatible with both Zune Marketplace—whether that means downloading on the fly, we're not sure—and Xbox Live. The latter means there's most likely going to be Live Anywhere implemented on the phone.
Also, the Zune Phone is going to be able to stream data to and from the Xbox 360, which means you may be able to watch those downloaded videos on your phone or stream music to your 360.
The Zune Phone's interface will be a mixture of Zune and Xbox 360, but may not be touchscreen, like the iPhone.
Since Microsoft plans to release it this (late) year, they will only have to play catch-up with up to 6 months of iPhone head start (iPhone's coming June) instead of nearly 5 years of iPod head start.
Source: Microsoft Zune Phone In the Works [Crunchgear]