The unit fits onto an iPhone 5 (and 5s) and uses an iPhone app for control, display and recording - including movies - linking via USB. I couldn't find any information on spatial resolution but my guess is that the display is something like 320 pixels across. This is augmented by the ability to blend in a visual image to provide some detail to help identify features. The thermal core is FLIR's Lepton, which is a tiny microbolometer-based unit designed for consumer manufacturing scale. The thermal range for the scene is zero to 100 Celsius with a resolution of a tenth of a degree, which should suffice for most consumer uses and will certainly pick out a person in the dark.
You can find out more either by visiting the FLIR ONE web site or on the CES video that the BBC shot.
What is telling is that much of the FLIR promotional material is aimed at people who don't even really know what thermal imaging is or what it can do. A thermal image is (IIRC) regarded as a search in the US so there may be privacy concerns but a thermal image of a person does not show any significant detail. (That judgement was based partly on thermal imaging devices not being generally available to the public.) Hopefully we won't see any of the hysteria that greeted near-infrared photography and its so-called (and insignificant) X-Ray capability! Oh, and to save you asking, it's the area between the eyes and the bridge of the nose that best shows the body temperature, not the forehead.
I see this as a really significant piece of kit and welcome FLIR's initiative. Worldwide launch is Spring 2014 'at popular retail outlets'.