It is already affecting where I choose to drive to. Used to just hop in and go, now I do the math before hand ( I HATE MATH GRRRRRR) how many miles is is one way etc. As prices rise, I think many will be cutting way back on trips out, do more combining of trips around town in order to have gas to get where they "need" to go.
I drive a mini van 20 gal gas tank. I went to a quild meeting today that uses 1/2 gal of gas. I know some may think oh big deal, but......... as the price of gas keeps climbing, that half gal costs more. It adds up fast.