Why you should definitely not keep your iPhone in your breast pocket.
Because when you bend over to pick something up, it's likely to fall out. When the thing that you're picking up is on asphalt, the iPhone hits the asphalt. This is the result of an iPhone falling face down onto asphalt.
This public service announcement brought to you by the Union of Completely Clumsy Asshats (UCCA)

September 7th, 2009 at 5:40 am
Do you know about Otterbox? Check out the Defender case. Just bought a Defender for my hub’s new Blackberry Tour because he has a tendency to knock his holster off his pocket and the phone goes boingity across the parking lot.
I think the phone looks kinda like it’s wearing a robocop helmet, but it sure is effective.
http://www.otterbox.com/iphone-cases/