aakk9999 - 1:23 am on Mar 1, 2011 (gmt 0)
People are talking about penalty. I do not think it is a penalty. It is a new algo - this is not the same as the penalty.
For the sites that were hit - the rules on scoring have changed, and these sites have not scored enough to be ranked where they were before.
I think that with penalty it is slightly more simple - it usually points to one (or few) main reasons why the site was "hit" (or penalised or filtered out). It is easier to dig yourself out of penalty because it is easier to deduct why it happened.
With the new algo - the calculation rules have changed. For all what we know, it could have been (arbitrary) 50 factors that were all dialed up or down + perhaps (likely?) new factors introduced. This is why it is harder to figure this one out.