Microsoft frequently has SDRs (Software Development Reviews) where experts on a particular technology are invited to Microsoft to preview and comment on some works in progress. Luckily for the rest of us, a number of the presentations given during the WSE 3.0 SDRs were taped and they are online. Here is where you can find them.
This is a huge gift. I have been watching so far the WSE 2.0 to WSE 3.0 Migration presentation by Govind Ramanathan (a developer on the XML Messaging team) and it is just excellent. It's a treat to have someone who knows this stuff inside and out and is a good presenter giving the explanation.
If you have any interest in messaging (which, if you plan to do any development in the future, you ought to have) I highly recommend checking these out.
What's interesting to me about this particular session is that I have focused on starting new WSE 3.0 projects thus far and haven't delved into actually migrating current apps, though I do hope to do that with one of my VS2003/WSE2.0 production apps. So Govind is getting me thinking about some particular aspects of WSE 3.0 that I haven't looked at yet.
What is truly cool is how you can pull WSE 2.0 projects and run them inside of WSE 3.0. I do have some questions for Govind on this (it sure looked like he removed the reference to the WSE 2 API but since some classes have been deprecated in WSE 3, that was a bit confusing). However, since WSE 3.0 is really driven by policy, if there is no policy defined, WSE 3.0 will call the WSE 2.0 pipeline to process the outgoing message based on the code. So for example, if you have attached a UsernameToken in code and signed and/or encrypted in code, rather than policy, WSE 3.0 doesn't know how to deal with that, so it will ask it's friend, WSE2.0 to handle the processing for it. Really neat (and thoughtful - thanks folks!!) stuff.