(Great info on voting patterns in the 110th Congress, and provided more depth to the Bush Dog discussion. Check out the charts in the extended entry, especially the longer, second one - promoted by Chris Bowers)
Finally, I've managed to sit down and spreadsheet the 110th House rollcall votes up to the August recess. (I started before the Bush Dogs thing got going, but I can't help thinking that was a spur to getting me to finish it!)
So - let's look at the issue of rep loyalty.
There have been 846 RCVs in which Dem reps have cast 187,746 votes. Of these, 8,336 (4.44%) were cast against a Dem majority on the vote in question. Let's, for want of a better expression, call those rebel votes.