It sounds as though they will be using LOTS of new emblems based on entries, not just the winner. So if you didn't win theres still a chance that you might get to see an emblem based on your design in the game.
The most frequently submitted icons were retooled, refit and refined into a basketful of new icons for Halo 3. I would list the names of all that submitted those ideas, but the list would be enormous, and, frankly, I think you’d rather I spend my days getting the HUD and UI in Halo 3 to look cool. If you were one of the hundreds that submitted one of those ideas, pat yourself on the back and count yourself as a pseudo-winner.
So if you haven't already post the emblem that you submitted here. When Halo 3 releases on Sept 25th we can compare then to this basketful of new emblems and see if any of us are unnoficial contributors to the H3 emblems!
Heres my entry, it's the BanHammer. I suspect that this was a frequent entry.