Looks like Silverlight will be available on Windows Mobile 7
Excerpt from http://wmpoweruser.com/?p=13486
The above document confirms both Silverlight and XNA development. Silverlight is interesting, as we know it will not be present in the browser yet. XNA is however more interesting, as it is the same language used to program the ZuneHD and more importantly X-Box Live games, suggesting cross compatibility between the 3 platforms.