Existing members of Apple's iPhone Developer Program can login and download the new SDK, which includes an iPad simulator for testing new apps under development.
The site also presents an iPad Programming Guide that "introduces new features available for iPad and how to implement those features in your applications," as well as new iPad Human Interface Guidelines.
Apple says the new user interface guidelines outline "how to effectively use the new views and controls available to you to deliver unforgettable applications to your customers."
The SDK also includes new example code projects that "provide an example of how to accomplish a task for a specific technology."
Apple is also launching a new Universal Application binary format for iPhone OS apps that allows developers to deliver a single app that can take full advantage of the features of the iPhone, iPod touch, and iPad. This essentially wraps iPhone and iPad code into the same app package for easy distribution and management.