It's back after a seven year hiatus. IGN has the full scoop, and they report that developers Piranha Games have some ambitious plans, including 4-player co-op. They're also going to try and make the full range of mechs significant within the game via recon and intelligence missions: "it's not just a race to the heaviest, most powerful mechs. The designers want to reward you for picking a mech and sticking with it -- you will gain experience and become better at piloting your chosen mech, and that will translate into better accuracy and damage with weapon systems. This way, a player could specialize in a light mech throughout the entire game if they choose. It also means there are multiple playthroughs with different mechs." No release date as yet.
Lengthy CG -but-clearly-target trailer below.