Metal Gear Solid: Peace Walker was developed by Konami and Kojima Productions, released in 2010 for the PSP. Few info about the beta version are available thanks to Ravi Singh of The Snake Soup:
Around April 8, 2010 Kinsoku Jiko from The Snake Soup forums used the program CodePR to dig data from the Metal Gear Solid: Peace Walker TGS 2009 demo. While weapons and items that would be seen in the final game were found such as Pepsi and Huey’s Letter, left-over artifacts from Metal Gear Solid: Portable Ops Plus were found such as the Heart of Justice item.
Recently Ravi Singh has found material posted by Kojima Productions on their blog that is from a build of Peace Walker made prior to the first demo release. Of interest are the different HUDs (including one that is exactly the same as Portable Ops Plus), a different graphic damage meter and what looks like either an item or gameplay feature that allows the player to see the enemy more clearly. There is also a mock-up of what the beta graphic damage meter looked like in action as an animated gif image.
Blog posts are http://ameblo.jp/kp-blogcast/entry-10598028071.html and http://ameblo.jp/kp-blogcast/entry-10591306201.html
Thanks to Ravi Singh of The Snake Soup for the contribution!