I'm confused as to what the problem is. You are saying that (1) in Leopard and Snow Leopard, the arrangement of the desktop icons is reset each time you run out of memory? (2) And if you move the position of an icon accidentally, you used to just force quit Finder and the icon would be back in the original place?
For (2), that wouldn't be preserving the icon placement because you moved it and it didn't save the new position of the icon (as demonstrated by restarting Finder).