Found a bug.  This is with the downloaded package for mac os x Leopard (not snow).

I put a simple box on one layer.  I then added a layer and cut the box from the first layer and went to the second layer.  Did a paste in place.  Inkscape crashes.

Just tried it again with just cut and paste on the same layer..  Still crashes.  I get an error message that I assume to be from the OS asking if I want to relaunch.  When I do this, I get an Inkscape window that is full of garbage characters and missing icon buttons.