Major hardware announcements during the show included Microsoft's Project Natal and both Sony's PSP Go and PlayStation Move, while major software announcements included Left 4 Dead 2, Metal Gear Solid: Rising, Halo: Reach, Final Fantasy XIV, New Super Mario Bros. Wii, Super Mario Galaxy 2, and Monado: Beginning of the World.

The E3 2009 was greatly expanded in terms of size from the previous two years as it was reopened to all qualified computer and gaming audiences.

E3 2009 was held at the Los Angeles Convention Center with the show occupying the South and West Halls as well as the first floor.

The west hall housed both Sony Computer Entertainment and Nintendo as well as third-party publishers Activision, Bethesda, Capcom, THQ and Atlus.

The south hall housed a larger number of publisher booths, including Microsoft, Square Enix, Koei, Ubisoft, Namco Bandai, Warner Bros., Disney, Eidos, MTV Games, EA, Sega and Konami.

G4 also covered many exclusive game demos at E3 2009 as well as Steve Wiebe's unsuccessful world record Donkey Kong high score attempt.