Help with Photoshop technique that I'm assuming uses paths

ITWorks, a guy that is on the ultrashockforums (and maybe is here, dont know) has a really cool website:

My question is I can not for the life of me figure out how to bend a long rectangle, like he did with the green one on his splash page. If you enter his site, the background of it has the same effect, but all of the rectangles have it this time.

Anyone know how to do this? I’m assuming it has to do with paths, but I’m not very good with them so some guidance would be cool.