Brush stroke effect

I'm aware that it's not an icon, but I didn't know where else to go so hopefully it's OK that I ask here. If not, feel free to delete the post.

I came across this banner somewhere (unfortunately, I don't know who made it) and would very much like to know how to get the 'brush stroke' effect. Any help is greatly appreciated! :)





ETA: I use Photoshop CS4.