I copied the file pop.caf from Kitchensink to /Resources/pop.caf in my project. I cleaned the build, removed the app from the device and re-installed.
Then I sent a test push notification from the ACS console, specifying 'pop' in the custom sound field. When the notification was received on the iOS device, it played the default sound for push notifications instead of the pop.caf file.
Any ideas what's wrong?