Stealth where did you see that their is a map in halo 3 called compound?
If you watch this video of someone with the full game it shows the whole map list.

http://www.youtube.com/watch?v=n-Xn0U2NTws

This is whats on the list:

Construct
Epitah
Guardian
Highground
Isolation
Last Resort
Narrows
Sandtrap
Snowbound
The Pit
Valhalla