According to Konami's official website, Metal Gear Solid 4 will be released in Winter this year.
This of course goes against what Kojima Productions stated earlier this year when they announced that the game was delayed till early 2008. Perhaps they will announce something in their keynote during the Tokyo Game Show.
Currently Konami is showing Metal Gear Solid 4 both in playable form and in trailers at TGS. You can check out the latest trailer here.
Stay tuned to PSU for further information on the release date.
Source: Official Konami Website
The Kojima Productions area of the Konami website still lists the title as Early 08.