Here's some poll data that I don't believe has received much attention.
"If [see below] wins the Democratic/Republican nomination for president would you definitely vote for him/her in the general election for president in 2008, would you consider voting for him/her or would you definitely not vote for him/her?"
PERCENT SAYING "DEFINITELY WOULD NOT"
Obama -- 39%
Clinton -- 41%
Edwards -- 43%
Giuliani -- 44%
McCain -- 45%
Thompson -- 54%
Romney -- 57%
What's does that mean?
1. Sen. Hillary Clinton is no more polarizing than other Dems, and less polarizing than every leading Republican.
The problem is that the question is not a good measure of whether a candidate is "polarizing" -- it conflates familiarity with approval. In other words, some people may be answering "no" because they don't know anything about a candidate, while others are directly expressing disapproval. Hillary's 41% is likely to be concentrated in the latter group, while Obama's 39% is likely to be a mix of both. You can see this if you look at the numbers in context -- Hillary is the best-known candidate and thus has the highest percentage of voters saying they would definitely vote for her, whereas lesser-known candidates have much less.
A better measure of whether a candidate is polarizing is to look at their favorable/unfavorable numbers, as I've done in the past for Hillary. The most polarizing candidates will have high positives and high negatives approaching 50/50. And guess what? Hillary's most recent numbers, which come from USA Today, show that her unfavorables are in the mid- to high-40s. By comparison, the unfavorables of Edwards and Obama were in the low- to mid-30s. Don't believe the hype.