2009 was not an election year for either the President or the Congressional midterms, so it's a little difficult to accurately identify nationwide voting "patterns" when there was so little voting actually going on. But there were a few special elections, and they did clearly reflect the anti-incumbent mood the previous post talks about.
To put it in the context of what may have changed from 2008 election and voting patterns, I think it would be safe to say that Democrats, especially younger democrats, are less likely to want to vote at this time - that is, much of the enthusiasm of Obama's Presidential campaign has faded in recent months as the recession continues to bite and the oil spill weighs on the national mood. The emergence of the Tea Party movement signals a voter disgust with both parties, although it is a minority movement and somewhat fragmented. Lastly, I think older voters are much more likely to want to vote this time around - even more so than last election, and that is saying something given that senior citizen voter turnout is usually the highest among that age group.
I would say that one major trend that is heavily evident in the voting patterns of 2009 was the dislike of the establishment. Both major political parties were striving to reach the disenfranchised voter with different appeals to "populism." With an economy that still showed signs of struggle, as well as a fundamental challenge with being able to ensure material prosperity for all of its citizens, voters felt the need to lash out at the political system that they felt had not brought them into the political process enough and validated their voice and experience. Democrats used the target of big businesses and industrial commerce as an example of targetting voters' dislike for the establishment. Republicans used the Obama adminstration as examples of "insiders" and skillfully using the Tea Party and other organizations like them, they began to carve out a position that was ripened with anger and voter dissatisfaction. It was quite a radical shift to see the Republicans as a the party of Populism.