It's pretty free-form: for 4 weeks starting on Sunday February 1st, participants create one new thing a day. Choose your own themes, one per week (I don't know if I'll do this). Work in any medium. And post your work on the group blog every day. Again, I don't know if I'll post stuff on their blog, but I did sign up just in case. You can do that from their site here.
Play along with me won't you? :)