Jolla is a start-up from Finland, yes from the land of Nokia. Sailfish OS is based on a port of Linux based Meego OS, which supports android apps as well as native apps. Although not much of the specifications were revealed, the "Jolla" sports a 4.5-inch display, with 8MP camera and user replaceable battery.
There are snap-on covers available as well, wherein the back half of the phone is removable which exposes the removable battery. There are a few color choices including light blue, green, white and orange. The Sailfish OS in Jolla recognizes which color back-cover is on and adapts the theme of the phone accordingly. There's 16GB of microSD expandable storage as well. We'll have more on the Jolla in the coming weeks. Stay tuned!