Eric Enge has an excellent interview with Vanessa Fox, former Googler but extremely well respected SEO, on the topic of the Google Panda update.
I am not going to go through the interview here, you can read the full interview at Eric's blog and Eric always does a great job with his technical interviews.
A WebmasterWorld thread has discussion around the thread. The nice part is, any questions regarding the interview, Vanessa is going into the thread and clarifying.
For example:
I wouldn't say "in other words"... I don't know that Panda has anything to do with social engagement. (Maybe it does, but that's not what I was talking about.)
or
About the first post in this thread, keep in mind of course that I haven't worked for Google for a long time, so anything from Matt and Amit (and Maile, John, etc.) is definitive from Google. I'm just providing my opinion based on what I've seen and my past experience.
Vanessa has a unique approach to looking at SEO and to many, it is a breath of fresh air.
Check out the full interview at Eric's blog.
Forum discussion at WebmasterWorld.