To no one's surprise, the studio is looking for several experienced individuals to join the team. If you head over to the job listings page, you'll notice that 343i is looking for both a multiplayer designer and software developement engineer (first spotted by OXM).
The software engineer will be responsible for working on "the next generation of backend services to power Halo 4 and our new game saga." The listing also notes that experience in working on MMOs would be "ideal". With reports suggesting that Bungie and Activision's new game series is going to be a sci-fi MMO, perhaps 343i is hoping to face them head on.
In addition, Microsoft's Core Games Publishing team is currently looking for a software development engineer who will almost certainly be working on the next big (next-gen) Xbox-exclusive blockbuster. "MGS has a number of successful core franchises: Halo, Fable, Forza Motorsport, and Gears of War. Our job is to add new blood to this stable of AAA franchises. We have huge ambitions for what we want to accomplish, and we need a great software engineer to help us get where we want to go."
Bring it on! After all, the Xbox platform could definitely use a few more exclusives.