WPF supports vector-based graphics, animation, and video content in a way that is much more natural to the browser experience than Flash. It puts in your web browser things that look much more like desktop applications than like web pages.
So, why the hell are they doing this? A few reasons:
(1) - Development tools. They may be making the technology free to users who rely on the competition, but only Microsoft has the tools to create these experiences. Microsoft’s Expression Studio and suites are going to becoming must-have tools if WPF takes off.
(2) - Change of philosophy - Microsoft’s continued sales of Windows and Office, as well as support of the overall PC market, relies on good will among users. In the past, Microsoft used monopoly tactics to support Windows, creating proprietary technology, like WPF, that only worked on Windows and IE, and forced users to use Microsoft. Now, Microsoft realizes that WPF on a Mac does one thing: Make Microsoft look like an innovator and a friend to all computer users. WPF/E, if a success, will spread more good will than lock-in ever has, and that’s a huge benefit, including financially.
Sean Alexander saw what was going on, and made it a priority to get moved to the WPF/E team, so he’s got a lot to say, and will likely be your best source for news on this in the future.
Scoble also talks about a part of the Expression release, Expression Blend, which seems designed to compete with Adobe/Macromedia Flash. He explains why Microsoft did this, not to compete with Adobe, but because of Windows Vista. See, when developing Vista, the UI designers did their mockups in Flash, which had to be given to the dev team and completely rewritten in C++ code for Windows. The UI guys couldn’t touch the UI code, since it was in Flash, a completely different world, so Microsoft designed a tool letting them do UI while the software programmers worked on features. That is Blend.
Coding4Fun has a few WPF samples. Load them up on a system with the plugin installed and see why this is so amazing. Karsten Januszewski has one too. It’s amazing how good some of this stuff is. I want the Media Library example to use on my own site.