If the run is long enough I have to carry water, I carry my cell phone, ID, and a credit card. I usually run from home when someone else is home (and we have a garage door opener with a keypad so I don't need a key), but if I run from work/my car, I do have to carry some keys. If I am carrying water, I put the keys wherever the water is (and only carry the minimum). If not, I wear shorts with pockets, or my spi belt.

Sometimes I do run in a bike jersey (especially if I ride then run), and the pockets come in handy, but I can't exactly stuff them because the stuff bounces more.