For the Firefox 16 beta release, we plan to support only a limited set
of ARMv6 devices in the Play Store. Mozilla QA is still working on
testing a wider range of devices and figuring out exactly what type of
hardware can run Firefox reliably; we'll expand the supported device
list as soon as we have more testing. (And of course, users of untested
devices will still be welcome to download builds from Mozilla's servers
and let us know how they work.)