National Journal's liberal/conservative rankings for Congress are out (see them at NJ's website here), complete with a web applet that lets you sort by state, district, score, etc.
One significant development NJ points out: centrist Republicans are vanishing from both the House and Senate. For the 10 GOP senators who departed in 2008, the median conservative rating was 60.9--left of center for the party. While the median score for the 43 House Republicans who left was 73.3, centrists were more frequently replaced by Democrats, meaning more conservative seats stayed in conservative hands.
So as voters in moderate districts choose Democrats over Republicans, the GOP conferences in Congress get more conservative. Since the rankings are based on 2008 votes, National Journal has not evaluated the ideological consistency of freshman Democrats, though swing district pickups will, undoubtedly, yield some more moderate members of the Democratic caucus--as in 2006, when Reps. Jason Altmire and Patrick Murphy won in Pennsylvania and joined the Blue Dog Coalition of conservative Democrats upon entering Congress. Those two accumulated an average liberal ranking of 53.75 in the new report--far to the right of Speaker Nancy Pelosi's liberal preferences.
We'll have to wait and see how the freshmen vote in order to find out whether the Democratic tent has gotten much bigger after '08.