Hey, awesome. Long-time Guitar Hero developer Neversoft Entertainment appears to be working on a new shooter. Super sleuth website superannuation has discovered a recent LinkedIn job listing from the studio asking for an experienced level builder to "work on [a] new action shooter game." It's required that the builder must be able to "build realistic 3D levels and environments."
That's it--there's no tease or suggestion as to what IP, either old or new, Neversoft is working with. The current speculation amongst the blogs is that the studio could be resurrecting Gun. I suppose it's also possible that Neversoft could be working on a Call of Duty game. That's definitely more of a stretch: Sledgehammer Games, Treyarch, and probably even Infinity Ward, are all creating games based on the IP. Hey, maybe they're finally bringing back Bruce Willis and developing Apocalypse 2.
In addition to whatever this shooter is, Neversoft is developing Guitar Hero: Warriors of Rock. It's due out in September and has a campaign component narrated by the nastiest dude on the planet, Gene Simmons.