Just in case you missed it, the Tizen project just launched a brand new site at tizen.org. It's been substantially redesigned and updated to make it easier to find project information, and reflects the new look and feel of Tizen.
Application developers, check out the new http://developer.tizen.org (you can also find it in the dropdown at the top left of the new pages). You'll find lots of information on how to develop apps for Tizen, including Tizen SDK downloads, sample apps, and API documentation. There's also information on debugging and packaging apps. To ask questions and connect with other developers, check out the forums.
Finally, you'll also notice that the second Tizen Developer Conference has been announced! The conference will be held May 22-24, in San Francisco. More details, including registration and CFP, will be available soon.