Right now Silverlight (wpf/e) is not for the feint of heart - lots of javascript coding involved.

But Ray Ozzie just announced (as I'm sitting here in the keynote) at MIX that Silverlight will support .NET as a first class .NET development environment. So you can develop silverlight apps in .NEt. This means that the silverlight  runtime will include .NEt. And since sliverlight is targetted at macs also this means that .NET will run on Macs. I'm assuming that this will be a subset of .NET, but ..... pretty cool.