klark0 - 11:41 pm on May 4, 2012 (gmt 0)
List of 53 changes last month. Penguin seems not included in these 53, but as a side note at the end. This keyword stuffing improvement looks separate from penguin.
Keyword stuffing classifier improvement. [project codename "Spam"] We have classifiers designed to detect when a website is keyword stuffing. This change made the keyword stuffing classifier better.