TouchDevelop – a simple way to get started in programming with your Windows Phone

TouchDevelop is a simple yet addictive little programming environment for your Windows Phone. It's available from the Windows Phone Store for free, and it's made by Microsoft Research.

With TouchDevelop, you create scripts that can access features on the phone, read and write data to the web, and interact with popular social networks. Programming itself is done with a touch-friendly interface. TouchDevelop is also available as a web application, be sure to check it out.

Hmm, when shall we see Visual Studio for Windows Phone? :-)