I think I just stumbled upon the best theory... Thanks to
http://www.scarecrowmovies.com/ for posting his logs online.
There are a lot of pharmacy spammers that are using st.php to get to their URL's...
Example:
http://www.scarecrowmovies.com/st/st.../mirror/32238/
So I believe Google decided to screw anyone with st.php and url on the page. This doesn't mean other scripts are not susceptible to this same attack. It just means some Russian idiot decided to target ST since it is the most widely available script.