I'm not sure if I received a Google penalty or not. The PR for one of the sites I work on dropped to 0, but at the same time, SERP's went up for most of the keywords. <br /><br />The only thing I can think of that caused it was some kind of hosting setup glitch. Basically, they owned the .com and .net of their company name. The .net is the one ranked in the search engines, but instead of the .com forwarding to the .net, the same content would come up under either domain. <br /><br />I recently fixed the issues with a 301 redirect, so I'm hoping that will bring their PR up again. But so long as the SERP's stay good, I doubt anyone will care.