Yep, ST Campy ones are interchangeable too.
So are the BB30 Cannondale SI arms. It takes about 5-10 minutes to swap out the SI arms (and pedals) if I'm thinking straight, and 30 if I'm not and try and break things by accident (like trying to use the "stop" to pull the crank, instead of the pull fitting).
The one piece SRM sets are not interchangeable, like the DA. I dunno about the other ones (FSA etc).
cdr