Check out the
IMDB entry.
With Spider-Man being the biggest grossing superhero movie so far (and a kick in the backside for Lucas and co

) TPTB have decided to 'take a chance' on a sequel.
With the relatively huge success of the Batman franchise (don't mention Joel Schumacher) it is likely that was a strong possibilty right from the beginning.
With filming set to begin in January 2003, Director Sam Raimi and writer David Kroepp (also wrote Panic Room - I think he's great) are already on board, as well as the Maguire and Dunst. Also credited on IMDB are Sam Neill - as Doctor Octopus, and Bruce Campbell.
Bruce Campbell, whom most will know from Xena and The Evil Dead movies, made a fleeting appearance as the wrestling compere/announcer in the first SPider-Man movie.
Sam Neill as Doc Oc - hmm not too sure yet about that. I remember the rumours from way back when James Cameron was trying to get this movie made, with Michael Biehn in the title role and Schwarzenegger as Doctor Octopus - I never really got the image of the Austrian behemoth as this character out of my head.