One of the best sites for tips and news about Moveable Type is Learning Moveable Type. The editor of the site is Elsie Bauer. It’s been around awhile, but is full of lots of good info. One of the best things it does is help with instructions on upgrading, such as A Safe Way to Upgrade to MT 3.3. It was my prime instruction for upgrading.
Of course, the site Six Apart, which makes Moveable Type, Type Pad and other blogging tools is a good source too. For specific issues, I go there.