It has been confirmed! Hideo Kojima announced at the European Metal Gear Solid 3 press launch event that Metal Gear Solid 4 is in development and will be released on the Playstation 3. He also mentioned that MGS4 will start a brand new series with Solid Snake and the concept surrounding the next title will be "No Place To Hide". No other information has been released, but hopefully at the upcoming Electronic Entertainment Expo (E3) more information will be released.  

We will have more on this developing story.