During the 15 March 2010 Keynote Address at MIX10 Microsoft has revealed details of the free, yes free, development tools for Windows 7 phones.
Microsoft Visual Studio 2010 Express for Windows Phone is now available for free download from http://www.microsoft.com/express/phone/.
It includes the following tools:
Visual Studio 2010 Express for Windows Phone Windows Phone Emulator Silverlight for Windows Phone XNA Game Studio 4.0 CTP
So all you geeky developers can get started now building those apps for when the phone is released this Fall. Lets see what you can do!