Panthro - 8:24 pm on Oct 17, 2012 (gmt 0)
Saw something really weird not 20 minutes ago while checking rankings. In place of where my site usually shows up for the keyword was a site related to keyword, but the UK version of the site. Checked page two, and my site was nowhere to be found.
Went back to page one a minute or two later, and my site was finally showing up. Now the UK site was nowhere to be found. Only seen this behavior for that specific keyword so far, and it seems to be happening on and off.
Interesting. You should contact the owner of that site and compare logs.