Tizen, first appearing in January of 2012, is a complicated beast. Originally, this system shared a lot in common with WebOS (Linux Kernel, Web-based apps running in WebKit), which certainly makes it easy for web-devs to bring their apps to Tizen. As of Tizen 2, some of the components are not released under an Open Source license. And Samsung, a driving force behind Tizen (along with Intel), has transitioned Tizen to be its Bada operating system on top of a Linux Kernel. And, so far, no shipping devices (or announcements of future shipping devices) with Tizen pre-installed. Like I said. Complicated.