"Rumors persist about a Zune phone. I say it's totally unlikely for a pretty simple reason. The business model of Windows Mobile is totally different than Zune," Michael Gartenberg blogs or Jupiter Research.
"WinMo is a core platform and OS. No one has ever been successful licensing technology platforms to others and then competing with a device of their own," Gartenberg explains.
"There's certainly some likelihood of MSFT exploring a Zune phone but far more likely mobile Zune branded functions just get baked into a future version of Windows Mobile," Gartenberg writes.
http://weblogs.jupiterresearch.com/analysts/gartenberg/archives/2008/07/zune_phone_not.html