Being hacked, while slightly embarrassing, doesn't actually seem to be all bad news for companies. Burger King's Twitter feed, for example, gained followers during the attack and it is a lot of free publicity.
A sample tweet from the apparently hacked account:
MMM. THIS BURGER TASTES GOOD!!!!!!!!!! #MTVHack — HACKED MTV! (@MTV) February 19, 2013 
*But were they really hacked at all? This from Reuters' deputy social media editor Matthew Keys:
UPDATE: Apparently it was all a joke.
We totally Catfish-ed you guys. Thanks for playing! <3 you, @bet . ;)— MTV (@MTV) February 19, 2013