Depends on how you segment. For mobile its just a 1-2% tops (WP7 users). On the desktop I've heard something like 50-60%. Lets put it this way, there are 500

Depends on how you segment. For mobile its just a 1-2% tops (WP7 users). On the desktop I've heard something like 50-60%. Lets put it this way, there are 500M or so Silverlight enabled desktops. There aren't many things you can target that have such a large user base.