I think alot of webmasters have become scared with Panda and this has led to widespread changes. Some webmasters are noindexing large sections of weak content on their site and others are deleting all outbound links. This massive amount of change will surely impact the serps and create a ripple effect. Not to mention the chance of Google making tweaks to Panda or adding new quality signals to the algo. I am not expecting the serps to be very stable for at least a few more weeks if not months.