Wow, I am at the risk of becoming quite the FFG fanboi today. First Black Crusade and now this? Check out more info on these bad boys over at the FFG Site
Essentially, these are powered armor troops that have jump movement, and can zip across the battlefield slaying infantry squads (Grim Reapers) or smashing Robots (Tank Busters). They also mention a power punch (like a power fist I would guess) which probably makes them beast in close combat.