Thermostat makers aren't exactly known for their rapid update cycles, so we've been wondering just when a company as unusual as Nest would try its encore. If a new FCC filing is any indication, Tony Fadell and company aren't resting on their temperature-controlled laurels. While we don't know if it's a thermostat as such, the "home monitoring device" at the US agency sports Nest's familiar circular shape while tossing in some previously unseen ZigBee wireless -- a clue that there's home automation harmony afoot, either with other Nest units or with third-party devices. It's also apparent that Nest is keeping WiFi and won't venture far from its internet-friendly roots. All of the firm's secrets will be revealed in March, although we'll side with Zatz Not Funny and leave the possibility of an earlier announcement that helps us lower our heating bills.