The comic is an official continuation, written by Joss. It takes place several months after the finale (though they promised to do a flashback later).
I've been reading it, but I don't remember which issue # I last got. I'll check later. I think it was #2. (Where we find out the refugees' destination/caretaker.)
For those who aren't aware, there's also a Buffy comic that's the official continuation of the show. The first several issues were written by Joss, but then he went to go write Angel and put someone else in charge of writing Buffy. Still, well worth the read if you're a fan of the series.
Lab, what did you want to know about?
