GG denies that Google implemented an over-optimization penalty.
[Link to quote
"Has Google applied some sort of OOP or filter to the algorithm since the Florida update or was the drastic change in SERPs purely the result of new ranking criteria?"
It's the second one. People post around here about filters, blocking, penalties, etc. etc. A far better explanation is "things which used to work before don't receive the same amount of credit now." It's natural for people who are way out there with their linking strategies or their page-building strategies to think of a drop as an over-optimization penalty, but it's more realistic to conclude that Google is weighting criteria differently so that over-optimized sites just aren't doing as well now.