The Tizen Project, a coalition between Intel, Panasonic, Samsung and a number of mobilecarriers, has released the first non-beta release of Tizen. It consists of the TizenOS source code and a software development kit (SDK).
Some of the new features since the beta version are a new simulator for running and debugging web apps that runs inside a Webbrowser, and an improved emulator.
The OS now contains new POI and route searching features in location-aware apps, Peer to Peer connections through WiFi Direct and better HTML5 and Camera support for the Webbrowser.
The new SDK can be downloaded from the official Tizen Project Page here, which also has a full list of the available Features.