Google are doing something very strange at the moment which allows you to check if a domain has been hit by a Google Penalty!
The trick was spotted on Mediadonis earlier today. All you need to do is type in hyves as the subdomain for the domain you want to check, e.g. http://hyves.seoptimise.com, and then view the Google Toolbar PageRank which appears when the page loads (in most cases a 404 error):
“You will now get one of three different results for the pagerank of this non-existent subdomain -> PR7, PR4 and PR0.
PR7 means that the domain is perfectly fine
PR4 means that the domain got penalized by google
PR0 means that the domain got banned in Google”
While I wouldn’t expect this to be entirely accurate (for example, does it work for all types of penalty?), but based on the results so far it does appear to be a reasonably clear indicator of which websites have been penalised for selling links.
I also wouldn’t expect this to work for much longer, but it’s a very interesting and easy way to check if you’ve had a penalty applied to your domain. hyves.seoptimise.com displays a PR 7 so I guess that’s good news, I’ve spotted a few PR4′s appearing for web directories too. Can you find a PR0 before Google fix this? ;)
Update: Google have now fixed this and a PR0 now appears for all non-existent hyves subdomains.