Microsoft is helping developers get started with Windows 7 development by providing the Windows 7 Developer Guide. The Windows 7 Developer Guide provides a high-level overview of Windows 7 development and summarizes the advances in Windows 7 for developing rich application experiences.
Here a few of the areas that looked interesting:
I found the guide to be a good high-level starting place for Windows 7 development. You can find the latest version of the Windows 7 Developer Guide at
http://code.msdn.microsoft.com/Win7DeveloperGuide.