Yes, Metal Gear Solid 4 is apparently joining the pre-installation club! The game will be added to the growing list of games (like GT5 Prologue, We Love Golf, Devil May Cry 4, Haze, GTA IV, etc) that require PS3 hard drive installation. According to the display copy MGS4 boxart, the game needs a 4.6 GB installation. So all you other installation games, be sure to give MGS4 a warm welcome!
MGS4 Installation [GameSpy Thanks, Leo!]