that Ace of Aces mode is actually DownloadContent
Ace Combat 6: Fires of Liberation supports the following downloadable content:
* Super-High Difficulty Missions: Gamers that have mastered every aspect of the game will be able to download all-new missions that are extremely difficult and feature new enemy types that aren't found anywhere else in the game. The pilot that can complete these missions is truly an Ace among Aces!
http://news.teamxbox.com/xbox/14327/Ace-Combat-6-Update/
On another note, it appears there wont be any new planes for download, only paints
"BREATHE..... Keeps you calm under stress.... "
