Lost Planet 2
 

Well, on XBOX Live there is a a video under the "Spotlight" heading that has the head of the Dev-Team for Resident Evil 5 tell about a sequel that the "fans have wanted for many years..."

Then it shows the demo, which is apparently in-game footage.
It starts with a group of 4 troops in a skiff (a la Saving Private Ryan intro) traveling through a swamp when their air support comes under attack. They arrive at shore and jump out of the water craft, and it becomes apparent that a player has taken control of one of the characters. (At this point, maybe it's just me, but it looked as though the other 3 were human controlled, so I surmised that it would be 4-player.) The "squad" then proceeded to enter a jungle, and attack a group of pirates. The video then cuts to a battle taking place in a desert-looking landscape, where the "squad" is attacking more pirates. Then another cut, but this time it shows a player carrying a shield, and upon taking fire, slams in into the ground and it 'unfolds' into a larger shield. 2 other troops swing in behind the shield, one carrying a rocket launcher, which he fires, and the other just providing cover fire. Then the first player 'packs up' the shield and the squad presses forward into what I guessed was a makeshift pirate HQ. Then the video shows the name Lost Planet 2, powered by "MT-something 2.0" which is apparently CAPCOM's proprietary game engine that they "are very proud of"!

Then it shows someone answering questions about gameplay. He explains that the feel is the same, yet it is completely updated, and that the campaign will be co-op over XBOX Live. Also that the new MT-something 2.0 is a game engine that they are very proud of. After the questions, it goes back to the original guy, and he just says thanks for watching and he hopes that it is everything the fans wanted that they felt the first one lacked.

The video itself has a "E3 behind closed doors" kind of feel to it. Like, it has the lead guy explain a bit about it, then shows the video, then questions are answered, and then back to the lead guy to thank everyone for coming.