Hey Chuck!
At least we're fortunate to live in happier times, when the collections can travel around a bit. I got to see the Hessian exhibit in 2008 when the Louvre loaned the Museum Fridericianum most of the items that the French confiscated in 1806-7.
The really tricky issues are the imperial-era collections of places like Paris, London, Rome, and Berlin. I read somewhere that Egypt makes an official request to get the Rosetta Stone back, every year, just to make sure they're on record each year, claiming it.
best,
Sam