Gift-wrapped packages

Can you carry gift-wrapped packages in your luggage on international flights, or will the packages be opened?  Does it matter if you carry them in checked luggage vs. carry-on?  I've only taken a gift-wrapped package in my carry-on once on a U.S. domestic flight, and it was opened, but this was a few days after Sept. 11, and it was because it was lead crystal that didn't show up on the X-ray. 

I've traveled with gift wrapped packages, but I've always packed them into my checked luggage, just because carry-on luggage is subject to much more scrutiny; so I would think the risk of the gifts being opened would be greater if carried aboard.

I have traveled with wrapped packages in checked luggage only. So far nothing has been opened but it would not bother me if they were. Only takes a few minutes to re-wrap.