Army of Two isn't allowed to have numbered sequels, because they'd sound pretty stupid (e.g. Army of Two 3), so we'll just have to accept that the newly announced Army of Two: The Devil's Cartel, is actually Army of Two 3.
Th game will be developed by the same studio that developed the first two games, EA Montreal, however they have been renamed Visceral Montreal.
It's also going to be arriving quite a bit faster than we ever would have assumed. While it's not hitting in 2012, it will be launching in March 2013. EA has said that this is intended to be a reboot of the series, striking a grittier "more mature" tone. Which we assume means there will be less high-fiving over corpses.
"With meaningful, seamless co-op gameplay at its core and explosive new tag-team features, gamers will have to work together tactically and strategically as they push through a city dominated by one of Mexico’s deadliest drug cartels."
The game will follow a set of new characters named Alpha and Bravo as they presumably work to take down the cartel as an... Army of Two.