According to Kojima, MGS: Peace Walker on the PSP contains a big surprise and will make everyone go out and buy a PSP. Of course that is if they don't happen to own one already!
<blockquote>What should we be looking forward to the most with Peace Walker? "In terms of volume, I mentioned onstage at TGS that the script is as thick as Metal Gear Solid 4's," Kojima noted. "I'm putting everything I want to do on a portable console into this game. I haven't announced this yet, but there's another feature in here that will surprise people, to the point where they'll want to go out and buy a PSP right now!"</blockquote>
News Source: <a href="http://www.1up.com/do/newsStory?cId=3176464" target="_blank">1UP</a>