Sprint has released a special developers’ guide to the upcoming HTC EVO 4G to help third parties take advantage of technologies only available on the EVO 4G, namely the 4G connectively, HDMI output, and secondary camera support. From the guide:

This documentation covers additional functionality that will be available for the HTC EVO 4G Android device. This documentation is intended for the 3rd party developers who want to start developing applications for the device prior to official launch of the product.

To learn more, check out the guide.