The Web Applications Working Group has published a Working Draft of The Screen Orientation API.
The Screen Orientation API provides the ability to read the screen orientation state, to be informed when this state changes, and to be able to lock the screen orientation to a specific state.
Probably the most interesting feature will be the
lockOrientation() method, allowing the developer to force the page to be viewed in a specified orientation.
This Working Draft is an update on a previous version published in May 2012.