tedster - 5:42 pm on Jun 29, 2012 (gmt 0)
Here's how I see it. Exit Rate captures people who saw one more than one page, but then left the site from a particular page. It might also be that they finally found what they were looking for there, that's also true. But Bounce Rate tends to be quite noisy for many, many reasons. I've seen healthy sites with bounce rates from 20% all the way up to 70% - and these were all VERY healthy sites.
Using internal Exit Rate (especially if you filter out the bounce pages) can often offer insights beyond all that Bounce Rate noise - clues about where a site is weak, shallow, thin - whatever you want to call it. And that's what you want to fix to address a Panda problem.