I initially thought some of these replies were a joke. If you can afford a cell phone and you have one, why not have it with you on long(ish) rides. It's not fun to break a spoke or flat for the third time 60k from home with nothing but Canola crops and speeding semi's to keep you company.

I trust you carry ID (not the national security type - the this is who I am if I am close to death and you need to contact someone to claim the body type.) And maybe some money for an espresso, or a slurpee? I keep those and my phone in a small zip lock bag in my jersey pocket. When I am casual riding or comuting the same fancy, non-Italian design fits in nicely to one of my pants' cargo pockets.

Simple is sometimes best. To me (and I'm not a fear monger) but any ID and communication device should always stay as close to the body - you might get thrown from your bike, you might get bike jacked, you may want to give your bike to that lovely, lycra clad cyclist that has flatted....