wpmu education

Hey all,

I've been using wpmu for almost a year. I'm wanting to get a better working knowledge of all the nitty-gritty details. I know some basic php stuff, but I don't know where to go to educate myself further.

The development here has been significant in helping me resolve issues and get a better understanding, but I'm really wanting to dive deeper. Any suggestions?

Of couse, the more practice and experimentation I do, the more I discover, but wondering if there are good resources, books, classes etc. for learning more. Thanks again and again!

-james