Obviously housing downriver continues to be affordable. It might not actually be the prices that are going up, it could be that larger houses are selling better than small ones.
If you graph it out, it is not quite so optimistic. The Michigan Realtors measure of sale price jumps around a great deal. On the other hand, 2010 as been over 2009 for 4 of the past 5 months. This means it is not getting worse.