Recently Kojima-san of Kojima Productions came out to tell everyone that 'Metal Gear Rising' was still in works but now called 'Metal Gear Revengeance'. The original trailer for the game was shown a while ago now (remember Raiden cutting up the watermelon with his sword?), and all press sources had been very quiet since that day. Kojima-san also came on to twitter to tell all the fans that it will NOT be a direct sequel to MGS4, and will merely be a side story of the franchise focusing on Raiden.
Now, Konami have posted a video online of both Hideo Kojima and Atsushi Inaba, of Platinum Games, giving more information regarding the project. The game is now being developed by Platinum Games, who already have stylised action game Bayonetta under their belt, and is looking very promising.
Here is the link to the interview: Source