tedster - 7:15 pm on Feb 27, 2011 (gmt 0)
Don, you're talking about rankings, I assume - not PageRank. My first thought is that your site might be caught in a domino effect because pages that link to your site were affected. For some reason, it seems like outbound links from the top targeted pages now have less value than they used to.
I still don't have 100% definitive data to establish this domino effect, but a few people I know have also noticed that it seems to be happening.