There was a brief discussion about Microsoft's WPF/E on the Streaming Media list and Brian Lesser posted a link to this video, an interview with Mike Harsh, a program manager on the WPF/E team (WPF stands for Windows Presentation Foundation and E stands for Everywhere). Note that this video was recorded quite a while ago.
I watched the video and took some notes. Here's a summary (from a Flash Developer's point of view):

  • WPF/E is a subset of and for this reason does less than WPF
  • Microsoft will develop plugins for Windows and Mac and while they 'care about Linux' they're not going to supply a plugin but let 3rd parties take care of that (shows how much they really care)
  • the target runtime size will be 2MB (similar to the Flash Player which is 1.1MB to 1.3MB)
  • the programming experience is different to Flash (but not really different to Flex)
  • Mike seemed to get excited about the fact that 'you could have text and fill it with video or rotate it or stretch it' (oh dear)
Someone explain to me how this technology (which has yet to be released and proven) can do anything that the Flash Platform can't (do better)? Fill text with video? Come on...
I can kind of understand why Microsoft gets excited about content rendering reliably cross browser (they showed a clock playing on Safari on the Mac and Firefox on Windows and... wait for it... it looked identical. Yawn.), but I can't share that enthusiasm because it's common place for us in the Flash camp.

This looks like a copycat technology to me. XAML looks like MXML to me. The runtime like a copy of the Flash Player (minus real cross platform support and penetration). And the authoring won't run on a Mac if I understand that correctly. Fair play to Microsoft for trying but so far I haven't seen anything that impresses me. None of the demos show anything useful, like a real life RIA.
I know I am biased but if I was an investor on Dragon's Den I'd now be going: 'Sorry but I don't get it and for that reason I'm out.'