In a perfect world they'd have a client for just about every device with an internet connection.
In an imperfect world, this is WotC, the guys that brought you the Online Character Builder.
I'm pretty sure you don't need to write apps in Silverlight to run on the 360.... but unfortunately it's not a Silverlight VTT that could be easily ported to run on Xbox Live and my Windows 7 Phone.
I'm pretty sure you don't need to write apps in Silverlight to run on the 360.
You need to have an xbox?! I'd find it incredibly hard without having one...What makes people think it would be so hard to DM or play on an xbox?