Anyone know if 2 XDCAM EX cameras can be genlocked (I'm producing a live action 3D feature)?

Sorry but there is no provision for GenLock on the PDW-EX1.

However it will most likely have the option of Free Run TimeCode, in which case you can use the camera's wireless IR remote controller to set and start identical TC on two cameras simultaneously.

Will that syc the clocks so that frames are exposed in sync or will it mearly make it easier to align clips in post that are up to half a frame out of sync?

Does the Free Run method also sync the shutters? Is it that operating the cameras with frame-accurate time code synchronization by definition means that the shutters would also be synchronized? Thanx again

Free Run TC just makes it easier to align clips in post. It does not sync the shutters. This method is just a work-around and not a real substitution for GenLock, sorry.