Tried to help on a street's creation, but someone beat me to the contribution. (I'd clicked on the item, but when I "accepted" the confirmation dialog, it didn't take, and then it said the item wasn't needed anymore.) Later, though, once the street was done, I got an alert box from the rock: "Hey buddy, that was a hard one, but with your help we were able to upgrade that street! You did 0% of the work, nice."
I did get a teleport out of it, though, so that was a nice bonus.