If you're heading out to the Tokyo Game Show, Konami has
some instructions on what you need in order to snag yourself a demo of
Metal Gear Solid: Peace Walker. You'll need a PSP, of course, and a memory card with at least 200MB free. Make sure you have the latest firmware on your PSP as well. Oh yeah, make sure it's fully charged because nothing would suck more than to have your PSP go black in the middle of the download.
The demo will include 3 missions with one being single player, one being co-op with another, and one allowing up to four to play at once. They say the demo will vary slightly from what's at the booth so it might be worth it to check out both. Pretty cool way of Konami to distribute this demo around I say.