Make sure the Apple Developer Kit (latest, I think) is installed.

The egg is stored in:

Developer/Examples/Quartz Composer/Compositions/Conceptual

This is where examples for Quartz Composer (a graphics creator for making graphics in programs such as Front Row and Cover Flow) are stored. These have been made by Mac staff.

Whilst a lot of them are genuine helpful examples, one seems to be made just for a laugh.

There is a Quartz Composition named 'Timeline.qtz' featuring a head (of whom, I'm not sure) eating squares labelled 'GPU'.

I doubt this has any useful purpouse, so it must be an egg. If anyone knows who this (the head eating the GPU) is, please leave a comment!