They probably have a record of websites visited. But I don't think they would even bother checking up on me here... It would be a bit intrusive if they did.

My first IT job, about 6 years ago. there was a controversey surrounding a VP and his secretary in the NY office. A bunch of people from the company were bsing about it on the Yahoo boards, unaware that the company was tracking them (there is a precedent when it is about the company and using company equipment, although that obviously not the case in your case), and quite a few people were unemployed shortly thereafter.

Not saying its right, just that it happens.