interesting device, but I think it would be relatively expensive? and you'd also need glasses with the special seal or whatever it is in the bottom.
the thing that jumped out at me, though, is that the server is still picking up the cups by the rim. is it that hard to train folks to pick up the glass from the side when serving? maybe I'm just thinking about that because our club will be serving beer at Gainesville's Hogtowne Medieval Faire in 2 weeks. that's always something that we have to drum into new member's heads when they're serving.