Almost definitely Flash-based
Most likely it is a small Flash (SWF) embedded object on the page. It continuously copies data to the clipboard.
I encountered this once when taking an opinion survey.
2 publicly visible posts • joined 30 May 2008
The DNS hack appears to have affected incoming email also. I was CC'd on an email which should have come at 11:30pm (28th May), but didn't know about the email until someone responded to the group today and I got their message. Several hours earlier I had no problems getting email from the same individual.
I guess the hackers got a truck load of email addresses also.