Many of the folks in the comments at that link seem to think this is a prelude to trading Matt Garza. It will be interesting to find out how many years and how much money he'll receive, relative to the option the Pirates declined a while back.
UPDATE by Charlie: Maholm tweets that he has, in fact, signed with the Cubs.
UPDATE by Charlie: It's for one year, $4.25 million (via MLB Daily Dish), with a $6.5 million 2013 option with a $500,000 buyout. That's just a fantastic deal for the Cubs, frankly.