"Interesting solution to irritating cellphone users": Via IPList.

There is one technique I have used successfully to alleviate the annoyance.

When someone talks on their cell phone, pull out a pen and paper and take notes. I do this in airports, especially. Usually folks move away, but if they ask, you remind them that it is a public space and all conversations are in the public domain and may be used by journalists or bloggers.

If someone is arguing on the phone with a boy/girlfriend or spouse, you can suggest that [insert name overheard] might be available for a date. If they are talking business, just do a Marlowe, look professional and don't deny you are an industrial spy.

It is funny that many people seem to think they have the right to a private conversation as they are shouting all over a public place. They hate it when people listen in. And taking notes? They can get very annoyed about that!

The pen is mightier than the phone! Try it, I think you'll be impressed, or at least amused, by the reaction. And you'll enjoy more peace and quiet.

IMHO, it also sounds like an interesting way to get the crap beat out of you...