The 65nm Xbox 360 codenamed "Falcon" has landed in the new Halo 3 special edition Xbox 360's.
According to the forum post from the user "JWSpeed" new 65nm "Falcon" can be found in the Halo 3 console that was built on August 24, 2007 as a part of lot #0734. You can also check it out by using the "JWSpeed" "flashlight" method to see if there is a more simple heatsink in the console.
The new 65nm is cooler and should keep the new consoles from doing the famous "Red Ring of Death". You can check out the post here.