Having just bought a new Macbook Pro running Maverick, and 2 Macbook Airs for my kids over the holiday, I can tell you that iPhoto and the rest of the iLife suite are not installed by default. As soon as you setup the Mac and get it running, Maverick will download all the iLife and iWork programs via the app store. On all 3 of these new macs, the icons were already present on the dock, but the programs weren't installed until they were downloaded.
My guess is you haven't yet downloaded the iPhoto program, so when you try to launch it the App store opens.