We're already expecting a Windows Mobile 6.5 announcement at Mobile World Congress in a few weeks, but what if Microsoft has something bigger up its sleeve?

Gigaom is speculating that a Tegra-based, Microsoft-branded phone may well be unveiled in Barcelona.

A few days months ago, Stacey reported on the rumors that Microsoft-branded smartphone based on Nvidia’s Tegra chipset. It seems those rumors might be true. Doug Freedman, chip analyst with research firm Broadpoint AmTech, wrote in a note to his clients this morning:

we have been able to identify NVDA’s second handset design win for the Tegra Applications Processor (our Jan. 12th note identified HTC). We believe that Tegra is also designed into an upcoming Microsoft smartphone (with a Qualcomm baseband solution). We believe that MSFT may announce one of the new phones at 3GSM.

Windows Mobile 6.5 and a Microsoft-branded phone at the same conference? That might be a bit much. But there's only one way to find out. Dieter, pack your bags.

(And thanks, Gigaom, for sharing that hilarious Zunephone video!)

Update: No way, no how, says ZDNet's Mary Jo Foley.