Mark Pilgrim collects links to Dorothea Salo's explanation of how templates work in Movable Type. I've pretty much figured the dang things out myself, but there are still nooks and crannies that befuddle me. Besides taking care of my intro text needs for future students hacking with me, I'm hoping there's enough depth to clear up some of my own confusion.
Memo to audience: stuff like this is why MT is the tool of thought leaders in weblog tech