Donique,
I will step up and admit that I have floated a papyrus between 2 sheets of glass, but I used a thin bamboo frame around the outside and a piece of quarter-round to finish off the back. I attached it with very tiny dots of cornerweld in two spots (about the same spot as float-mount hinges would go). That was enough to keep it in place. I also told her that it might not stay in place, but that has been several years ago and she has not brought it in to be fixed...yet.
I explained first to my customer all the baaadd stuff that could/would happen to the piece. She was a good repeat customer, but very bossy and also very wealthy (read...used to getting her way). Cost was not the issue, she just wanted it to look a certain way. I figured that it was her (cheap, easily replacable) art and after educating her about the possibilities I had better do it her way or risk losing a customer.
Right now I have a customer who wants to do the glass, no frame thing with an old "the Graduate" poster. The poster is extremely tattered. It belonged to his uncle who had it hanging up for years with thumb tacks. Again, this is not due to money. He spends lots on framing, he just wants this to look a certain way. Bob, the link to the Stand-Offs was great. I've been scratching my head over how to accomplish this without my magic wand. The problem with the clip/string thingies is that they show through the glass, and also they are intended to be used with one sheet of glass and a layer of foam-core, so 2 sheets of glass are not thick enough to be held together tightly enough.
As a side note, let me just say that I have a limit as to what I will do even to please a customer. There are lots of things I would refuse to frame in this manner, even at the risk of losing the customer.