We recently announced the release of IIS Smooth Streaming Client 1.1 for Windows Phone 7 (link). Shortly after, Microsoft also announced release of client’s companion Silverlight Media Framework (SMF) 2.2 (link). SMF utilizes the client and offers easier app development for Windows Phone 7 through rich controls. I would not get into this more at this point of time. You can always find more documentation on that online.