I observed Panda testing some time before it was introduced. Google apparently had been testing Panda on AOL search. I always check my positions in AOL (enhanced by G) And somewhere before February noticed my positions down and looked for a reason why AOL punished me... Couldn't find a solution there.
Later on, after the first wave of Panda, my positions matched AOL "Panda testing"
Right now i am seeing the same scenario, all SERPs messed up again and unfortunately my key phrases went "puff" from search.
I was wondering if anyone can confirm my observations.