Security vendor F-Secure was defaced a few days ago by a turkish defacement crew.

"So how did this happen? The server itself is quite well hardened, but the web forum software had an unannounced security patch silently released by the vendor nine days ago. The defacement gang learned of the vulnerability and went through the net searching for vulnerable forums and changed the front page of such forums to their "greeting". "

Forum Link: http://www.f-secure.com/weblog/archives/00001336.html