Actually it's from an anime that's yet to be aired .. XD;
it's called 'Black★Rock Shooter' .
There's a vocaloid song of it already, i think that's what it will be based off ..
http://www.youtube.com/watch?v=EWSeSlH-Gdw
that's the trailer to the anime .
if you search around youtube a bit more, it's not hard to find the full version of the song too .
I'm really looking forward to it XD;