Conservatives leaving the Democratic fold has been a big part of the Republican resurgence over the last nine months, but the GOP still isn't doing a particularly good job of winning over moderate voters.
Last April we found 58% of conservatives identifying as Republicans and 21% as Democrats. Now the spread is 65% Republicans and 11% Democrats. Obama's first year and the health care debate in particular clearly has caused Democrats to lose some of the voters on the right flank of their party- of course it's worth noting that in many cases those are the folks in the party who voted for John McCain to begin with.
It's a different story with moderates though- they are actually leaning slightly more Democratic than they were last spring with 48% calling themselves Democrats and 15% Republicans- compared to 45% Democrats and 18% Republicans in April. The larger shift among conservatives toward the GOP has led to the overall improvement in their party ID gap but it is interesting to note they're not having a lot of success with the center.
I know Republicans get gaga with announcements like the one today that Gallup showed more conservatives than moderates at the end of the year but you still have to keep in perspective that there are barely more moderate GOPers than conservative Democrats.