When people want start learning about .NET in general or a specific subject like Silverlight or security, can be send to the "How Do I?" videos. I do this myself a lot of times, because a lot of videos aren't 60+ minutes. Just as a reminder to myself, the root url is this one .
I hope in the RTM you'll get more help solving your WCF Ajax problems then I currently get, because I'm getting mad from time to time. In my quest for getting things to work, I learned some stuff I wanted to share. Read: have a checklist for myself because I tend to forget this kind of stuff...