The archaeological world was somewhat surprised when the Louvre Museum agreed to hand over anicent Egyptian fresco pieces over to Egypt. The pieces were bought by the Louvre, however, it was later revealed the pieces were originally stolen.
Egypt threatened to stop working with the Louvre unless the fresco parts were returned. This has been the standard way Middle East countries have been able to have national artifacts returned from former colonial overlords. Now Egypt is hoping on ridding the wave of success and have the British (temporally) return the Rosetta Stone.
Right now observers are watching to see what Egypt does to get the stone back. If it merely asks then nothing is new. However, if Egypt threatens to cut off cooperation and follows through then the archaeological world will enter a new realm of interstate relations. This would become the first incident where great damage is done between states because of a fight over a long-ago taken item. Recent stolen items are expected to be returned but so far there seems to be a statue of limitations on artifacts taken before the late 1800s.
Right now everyone must wait and see. The fate of countless public and private European (and some American) collections hang in a balance.