Awesome... PS Forum member Gamble_STARS posted a link to a PSP demo (in Japanese) for Ace Combat Joint Assault! (he posted 2 links, but they are just mirrors of the same zip file)
[Check out the post here]
Direct links to the demo:
The demo is 117 MBs big(!)... I'm downloading it as I type. Can't wait to play it-- I've said it before, Ace Combat Joint Assault is my most anticipated game... out of all my consoles even... though I must admit Kirby's Epic Yarn (Wii) is also right up there on my drool-meter.