Want to read political scientists forecasting the midterm elections?
The political science journal PS (can you guess what it stands for?) solicited a number of articles forecasting the coming election and kindly left them outside the paywall. Read them here. James Campbell's survey notes that if you tally together 2006 and 2008, Democrats won 54 House seats. One of the interesting metrics in this election will be whether all of those gains are wiped out, or Democrats remain ahead of where they were after 2004.
Campbell, for the record, predicts a 51- or 52-seat gain for the Republicans. That's more than any of the other models foresee, but it seems plausible to me.