TypeScript is available under an Apache 2.0 open-source license.
You can learn more about the TypeScript project, download an early preview, read and discuss the language specification, explore the online playground, and peruse the source of the compiler on the TypeScript project site on CodePlex, with git.
In this video, Anders Hejlsberg introducing TypeScript:
At about 43:58, Hejlsberg opens up Internet Explorer, revealing an "internal preview" version of the Bing's home page, showing off some new features, "As you can see in this screenshot below, centered in the image are navigation controls that would appear to allow you to pan and zoom into the image, as well as a full screen icon to the right of the page (just to the right of the Facebook Like button). Whether this links to Deep Zoom imagery, a tipster François suggests (via), which could possibly be Canvas Zoom imagery using HTML5."
In the video below, Anders Hejlsberg, Steve Lucco, and Luke Hoban get us Inside TypeScript: