I saw it first anti-clockwise, but after a little focus I turned it around. Now for some reason whenever I look at it it's going clockwise, and it's even harder to turn around.
It's funny what triggers it too. A friend of mine saw it anti-clockwise all day, and couldn't turn it around till his wife touched him on the shoulder.
Edit: If you can't turn it around try using the suggestions there. Do maths in your head, or sing a song. Didn't really work for me, but others have claimed it did.