What makes a possible Microsoft Surface phone all the more worrisome for Nokia is that unlike other handset manufacturers that produce Windows Phone models, Nokia is largely dependent on the OS. For example, if a Microsoft Surface model were to, well, surface, HTC could just concentrate on Android as could Samsung, Huawei and others.
Last October, pictures allegedly of a Microsoft Surface protoype leaked. The handset prototypes, codenamed Juggernaut Alpha, are supposedly kept in Studio H at Microsoft's Redmond campus, guarded with the same intensity as those alleged alien bodies that are said to be kept at Area 51. So far in 2013, we have not heard much about a Microsoft phone although some of the last reports last year hinted that such a device could reach the market in the first half of 2013.
source: NokiaForm20-F via BGR