This is the COOLEST thing I've learned about Photoshop in years!
Removing objects on overlapping images in CS3:
1. Import layer stack (I prealign them in Autopano)
2. Convert layers to Smart objects
3. stack mode = median
4. Voila
Creating normal multiple exposure:
1, 2 as in previous
3. stack mode = minimum
4. Voila

Ok, images suck, shot against sun, not really cared about nodal point etc., not even AEL - but look, method works great for objects on bright background
Bad thing - method doesn't seem to work against dark background (on the right) or, perhaps I should try different stack modes.

This one was manual which is ok when moving objects do not overlap, but when they do - it's very tedious and not always possible. Here is where smart objects stacks will save you!