The domain registry watchdog Fusible reports that Microsoft's brand protection partner snapped up the full monty of HaloInfinity-dot-whatever domain names—except for a big one—which likely tips off some kind of activity or release involving that title.
Joystiq hilariously notes that haloinfinity.com, not among them, is from the looks of it a placeholder site that for now offers advice to Japanese men who are curious about baldness solutions. Speaking as a bald bastard myself, I can say that "halo infinity" aptly describes the toilet-seat pattern of my hair.
While Microsoft is not officially confirmed as the buyer, Fusible notes that MarkMonitor, the actual buyer, is the agency that registered no less than Microsoft.com. None of the domains redirect to any website as of the time of writing.
Also registered by the same agency: SpartanOps.org, SpartanOps.net, and MorethanJustamap.com