Tofias notes how different the Tea Partiers are from the GOP caucus as a whole:
For the 111th House, the mean of the Tea Party Caucus members on the first dimension of DW-NOMINATE is .7 and for Republican non-caucus members the mean is .61. On the second dimension, the Tea Party Caucus mean is .15 and for non-caucus members it is -.06. Both these differences are statistically significant.
To me, though, the striking thing is how similar they are to the rest of the caucus. Yes, on average, they're somewhat more conservative than the typical GOPer, but not that much. Indeed, the most liberal Republican in the House, Walter Jones (NC), is a Tea Partier.