IF Month is a loosely-organized set of tasks assigned one per week for four weeks, from February 15 to March 15, 2009, hopefully coupled with a few informal live discussion sessions (location-dependent, of course). The goal is to get a group of participants familiar enough with the Inform language to produce some simple games, and to promote discourse on game design in general through the medium of IF.
The organizer is at CMU in Pittsburgh, so that's where the initial "location dependence" is, but interested people may be arranging other meet-ups.
Further details at the IFMonth Blog.
The personal note: CMU is my college stomping ground, and I've met Lea and some of the other CMU folks involved on various visits back there. They are cool. Check it out.