At present SEPME 6.0.1 (and Symantec Mobile Security 7.2) can support Windows Mobile 6.5.  There is, however, no Enterprise release of AV software for the newer Windows Phone 7.

Symantec AntiVirus Product for Windows Phone 7 Platform (http://www.symantec.com/docs/TECH145141)

Customers interested in a Enterprise solution for this new mobile platform can make their voice heard by voting in favor of this proposed Idea.