I recently did a few upgrades and implemented a new site design. For the longest time my blog has had a pr 3 but when I just checked it and it has dropped to 0. here is the site in question - http://www.tomfmason.net. Since doing the upgrade my high quality backlinks should be 2-3x what they were before. I have some nice sites linking to me now that did not before(python.org etc). My traffic has also nearly doubled in the last two months. So I don't really understand the drop.
I don't know if page rank has updated or not. I suspect not because several of my other sites still have the same PR has they did last week, last month and hell last year. I am starting to think that I may have been sandboxed
I experienced similar case on one of my site. My affiliates contains good PR but recently some lost their pr and so is my site. Now i don't focus much more on PR.
This worries me a great deal from - http://www.google.com/intl/en_uk/corporate/tech.html Maybe I am wrong but from the info above it would seem that a sudden drop in PR would also likely end up meaning a large drop in SERP positioning as well.
Your website is likely in a heavy penalty from Google. - Is your content unique? or at least written by you? It does look like a scraped to me - Your website has 638 indexed pages in Google and only one link popularity in Google. How did you acquire backlinks for it? - Your website seem like a bunch of link farm. Why did you post content about poker and linking out to absolute off-topic website?
I had a look maybe when you upgraded the blog you forgot your old keywords and description, theres nothing there meta name="keywords" content="" meta name="description" content=""
It happens to me too they even close one of my blog for SPAM where I could not think of SPAM things which i have done in my blog ...They also drop my PR1 ranking in one of my health blog even I provide quality content . They might have detected something from your site or perhaps they just want to do it for only reason they know