A beta version of the Symbian Belle SDK has been released today on Nokia Developer. You can find it at https://www.developer.nokia.com/info..._One_SDKs.html
The SDK is recommended for maintenance work on your Symbian C++ / Avkon based projects. Its emulator offers the Symbian Belle look and feel, allowing testing your application's UI and adapting it to the new UI style guide (which is also documented in a PDF included in the SDK package).
For any new applications targeting the Symbian smartphones we recommend using the Qt SDK 1.1.3 (which includes a beta Belle target supporting Qt 4.7.4 and Qt Mobility 1.2) and the Qt/QML technology.
Please use this thread to ask questions regarding the Symbian Belle SDK (beta) release or to give any feedback related to the SDK content. As usual, remember to read first the release notes ;)