As of November 21, 2011, a large number of posts on Google groups seem to have been replicated to some adult chat rooms on Google Groups. This seems to be an attempt to game the search engine algorithm that Google uses and gain high search rankings for adult, spammy and potentially malicious websites.
We have blogged previously about how malicious hackers misuse SEO mechanisms to direct traffic to their malicious websites:
More discussion about this issue is taking place on Google Groups. We will present more details about this incident as we know them.