Murphy don't work like that. He wont drop the trigger on an empty chamber, he'll wait until you put a live round in it.
He must not have found out yet.
Ive been pretty abusive in my handling of the "empty" holsterless Glocks for the specific reason of trying to get the trigger to trip. So far, anything Ive done, short of actually pulling the trigger, has not been able to do so.
Even picking the gun up by the trigger, by hooking my finger around it and lifting has yet to trip it. If you dont get the trigger safety depressed fully, even with heavy pressure on the trigger itself, the trigger will not drop.
Im not saying that it "cant" happen, just like any gun "cant" go off while being holstered, just that I havent found it to be the big, bad, scary thing that you always hear in threads like these. Then again, Ive actually taken the time to try and prove it, and to the extreme, where I have a pretty good idea that most of those who tell you otherwise, probably dont even have a Glock, let alone even have bothered to try it out.
If youre reasonable in your handling and use some common sense (Plaxico wasnt/didnt) then I doubt youre going to have a problem. 99.5% of the time, I do use a holster with mine, but I do on occasion go without the holster as I feel the need.