Microsoft's TypeScript language has now reached official 1.0 status and is available for use on several platfroms, including VS2012/VS2013, Eclipse, and in source form.
TypeScript becomes a mainline language with the release of VS2013 Update 2 CTP. As TypeScript nears official 1.0 status, several key changes have been made to the language.
TypedMVVM is a collection of samples and libraries developed by Davide Zordan which enables enable developers to build Windows Store apps using WinJS, TypeScript and MVVM.
JetBrains has just released WebStorm 7.0 GA with support for EJS, Mustache, Handlebars, Web Components, Stylus, Karma, Istanbul, Compass, and comes with various enhancements.
Web Essentials, the extension introduced to add better CSS support to Visual Studio, has recently been updated with new tools for Visual Studio 2012, including support for TypeScript. It also includes automatic downloads of new schema files, so that HTML5 and CSS validation will always be up to date.