I'm wrapping up the "An introduction to ASP.NET Ajax" series today.
Although the posts were short and didn't go in depth, I hope I've been able to encourage you to dig some deeper yourself.
You can find all the posts here: this collection of ASP.NET Ajax 4.0 Beta Resources useful.
I'd highly appreciate it if you give me your opinion on these series. You can leave a comment or holler at me at Twitter.