A lot of developers ask if the application they developed runs well on IE8 and below, will the application still work fine on IE9. Very good question! I always have some problem to answer the questions well, now I have some good news to share.
The Internet Explorer 9 Compatibility Cookbook is available now. It is designed to help you understand changes in Windows Internet Explorer 9 that might impact applications that you developed for earlier versions of Windows Internet Explorer. In general, many changes in IE9 are designed to help Internet Explorer comply with broader industry standards, and other changes improve performance and reliability.
The cookbook includes information about changes to features, identifies features that are deprecated or removed, and describes general tools and guidance. Here is the outline of the The Internet Explorer 9 Compatibility Cookbook:
New topics will be added to this section as features are modified and as you identify areas where you need more information. Please take a look and provide some feedbacks.