thing is i think that microsoft see that they can no longer keep fighting on the app and os level, so they are moving to other areas and trying to shore up a controlling share in services and frameworks, stuff that can be server side rather then client side (a area in rapid commoditisation, or something like that).

thing is that they can use their existing market share in os and apps to leverage this, as they can more or less guarantee that if people keep their systems up to date (thanks to autopatching) they can roll out stuff like silverlight to all platforms by defining it as a critical update.

then they can say that for the webpages out there it will just work when a user browse/use a silverlight based page/service.

also, one can use the iis server and visual studio.net to have a integrated package for development and deployment. and as .net gets more languages under its belt, anyone that know a .net supported language can write a silverlight service.

i would not be surprised if microsoft finds a way to leverage xna for rapid game deployment on the iphone and ipod, now that they have a foothold with the exchange sync.