The film, which sees Iron Man battle his deadliest foe (The Mandarin, played by Ben Kingsley) also sees the drunken billionaire make use of his entire collection of Iron Man suits from their inception to the current-generation armor seen in "The Avengers." This army will number around 40 and be controlled due to Tony Stark (Downey Jr.)'s new ability to connect to a neural network within his main armor's cockpit. The "Extremis" story arc (which "Iron Man 3" is said to mirror closely) in the "Iron Man" comics was about a virus that, once administered to Stark, granted him the ability to network his mind to the machines he created. This allowed his mind to function at near-computing level, hence why he's able to control an army of Iron Men.
Latino Review confirms the story, discussing scenes in greater detail, including one where Iron Man leads his newfound army into battle against The Mandarin. CHUD points out that this newfound Iron Man army could have ramifications that extend to Marvel's "Avengers 2." With rumors of The Avengers tackling Galactus, Thanos or some other cosmic-threat, having an entire army of Iron Men certainly seems like a worthy addition to the roster. Joss Whedon would certainly look to incorporate this new addition to the Marvel universe into "Avengers 2," in an effort to further tie the individual universes together with his over-arching cinematic tapestry.