Firefox OS, and now I just read stories on Slashdot and Engadget about Jolla's pending release of their MeeGo-based Sailfish operating system.
While sources claim Jolla's efforts are open source, I'm concerned about a line from a source linked to in the Slashdot article that states, "Jolla's plans will not include open sourcing [Sailfish's] user interface layer
that it is building on top of the operating system platform." Which, of course, means that whatever Jolla ships won't be FOSS. At this point I have no idea if the non-FOSS UI layer is simply widget styling and branding (not a deal breaker) or something more crucial (potentially a deal-breaker). I hope to see this clarified soon.
An interesting difference/similarity between Firefox OS and Jolla is their marketing strategies. While Firefox OS seems to be targeting Sino-centric markets only obliquely (by targeting low-end hardware), Sailfish is targeting Chinese handsets directly. Just how this plays out globally will be interesting to watch.