UPDATE: Here are the contract terms according to SI.com: $8 Million in 2008 with a $4M bonus ($12M total). $12.5M in 2010, $13.5 M in 2011 and a 2012 $14M player option which is almost a guarantee to be picked up. And as I mentioned earlier, I'm about 90% certain he's earned 10/5 no-trade rights.
It's being picked up by multiple news sources that the Ryan Dempster Experience will call Chicago home for the next four years. It sounds like it might be for a total of $52M a year or $13M on average. That's a pretty good deal if he pitches like he did last year, not so much if he pitches like 2001-2003. For what was out there though and for how much the Cubs and Dempster seem to like each other, it sounds like the right deal. He really did have a fantastic 2008 season. His 152 ERA+ was good for third best in the NL.