By request, I took a look at this poll by PPP for Daily Kos and SEIU. Markos Moulitsas himself is hyping the poll as showing an enthusiasm gap, which of course was one big indicator of the electoral wipeout we saw in 2010.
I think that he's right, to a degree. However I read the figures as having two conclusions: First, the TEA party effect is still there, and Republicans are slightly more engaged than Democrats at this early point in the cycle. Second, the Union activism of this year is not having the same engagement effect with Democrats, that the TEA party, the ARRA, and the PPACA had with Republicans.
The key numbers in question: 420 Democrats were polled in this sample of registered voters nationwide, for an MoE of 4.8. 340 Republicans were polled for an MoE of 5.3. The excitement figures: 52% of Democrats are very excited, 31% are somewhat excited, and 17% are not at all excited. For Republicans it goes to 61%, 25%, and 14%. I estimate that there's an 81% chance that Republicans have a non-zero advantage among the very excited, and a 61% chance of a non-zero advantage among those who are at all excited. So I conclude this polls hows that Republicans have an engagement advantage over Democrats, per this poll.
Further, union activism around events in Wisconsin and other states has not evened up the parties. In fact, the Republican advantage among all excited voters was a deficit last month. Look at the poll taken five weeks earlier. At that time it was 381 Democrats (MoE 5.0), 371 Republicans (MoE 5.1). For Democrats enthusiasm was at 57/30/13, and for Republicans it was at 63/21/16. So in the last month we've seen Democrats shift down the enthusiasm spectrum about as much as Republicans have. In March the chance of a Republican advantage among the most excited I have at 72% (vs 81% this month), and among all those excited the Democrats were up 87-84, or a 62% chance for Democrats to have a true advantage (61% for Republicans this month).
So I'm forced to conclude, based on the movement of the Kos/SEIU poll that whatever bump in enthusiasm Democrats may have gotten over Wisconsin is not lasting, and what appeared to some to be a revival of unionism in America is not shaping up to be a left-wing counterweight to the right-wing TEA party. Republicans have more intense excitement about defeating Barack Obama than do Democrats have in re-electing him, and the trend is in the wrong direction for Democrats.