iPhoto came with my Mac. It is currently version 9.1.1.
When I open iPhoto, it pops up:
"An iPhoto update is available. Would you like to open Software Update?"
Then it offers me to start Software Update, but it finds no updates. Some people said I should check in the AppStore, but it asks me to pay if I want to take iPhoto from there.
I am running Mac OS X 10.7.2
I believe this update is to enable Photo Stream.