A few people on Twitter this evening reported that YouTube had been [maliciously] hacked. I clicked the first featured video on the YouTube homepage and was given a blank page that abruptly ended after a few comments containing attempted script code. Seems like a code injection attack exploiting incorrectly sanitised comments.
I run NoScript, so perhaps that's why I didn't see anything. If that's true, its for unexpected situations like this that I insist on running Firefox and with such an extension!
UPDATE: People are now saying it was /b/, the same mob that tried to send Justin Bieber to North Korea. They should have just left it at the latter; it was kinda funny.