We've been hacked! Oh, lordy no!

[Reverend Joe]

Wow, that IS weird... glad that's all that happened.

[TechnoMage of Shadows]

some advertisers are not genuine,
they are script kiddies with a few pennies, or a stolen credit card, they place ads with a reputable company,
those ads have "pass through" code which hijacks your browser when you leave the page that contains the ad and redirects you to a bad space.
They hit a major (online version) newspaper here that way some months back, not that the newspaper would admit to it,
but when the paper was notified about what was happening the entire set of ads was pulled within minutes.

All who have seen odd pages i would recommend running the free versions of SpybotSD and Adaware,
AVGFree is also recommended if you dont ordinarily have a virus scanner running. (many people don't)