Halo: The Cole Protocol will be the sixth novel set in the Halo Universe. Tobias S. Buckell, author of Crystal Rain and Ragamuffin will pen the novel, which reveals the location of the Spartan Gray Team and "takes readers into an unexplored conflict of the Human-Covenant War where unlikely alliances are formed and shattered..."
Bungie expatriate and Microsoft's Franchise Development Director Frank O'Connor had this to say on the upcoming book, which is slated for a Fall 2008 release, " Buckell continues an excellent tradition that’s now a solid aspect of the Halo novels, bringing a fresh new perspective to a limitless universe and bringing his prodigious writing talents to bear in ways that will surprise and engage fans of the series and newcomers alike."
The Spartan Gray Team has been mentioned twice in the novels. First, in the Fall of Reach in a single line:
"Assembled here tonight," she said, "are all surviving Spartans save three, who are otherwise engaged on fields of combat too distant to be easily recalled."
And another line in Ghosts of Onyx:
And what had ever happened to Gray Team on a mission far outside the confines of UNSC space, now missing for over a year?
Not a lot of info out about the book right now, but if it's coming out in five or six months then we're likely to be hearing more about it relatively soon.