I love it when someone gets to me to-do list before me. 🙂 It’s like an early birthday present. That being said, Jim over at BatavaTuesdays has written up a pretty thorough step-by-step process. I haven’t tested it myself, but it looks right so far.
The quick overview is to make a SQL backup of the WP blog, change the table prefixes and import it directly into the MU database. Yep, that’s pretty much it.
(Oh look, there’s another idea for a plugin if anyone wants to write one. 😉 )