It's not a pulley menu now, it's a push gesture on the lock or home screen. Push in from the left OR the right to see your Ambience options, although you won't see anything until you've "favourited" at least one Ambience image in the Gallery app.

Personally, I think this is a total waste of the "push" gesture on the lock/home screen which could surely be used for something more useful (another page of multi-tasking apps, perhaps?). It's not as if you're going to change Ambience every 5 minutes.