Will the iPhone 4 output 720p HD video using HDMI or a 30-pin dock connector?
UPDATE: The iPad 2 Digital AV Adapter is compatible with the iPhone 4. This will output 720p HD video to a compatible display with an HDMI connection.
It's not clear right now whether or not the Apple iPhone 4 will output 720p HD video to an external display. The camera is capable of recording at this resolution and videos can be exported from iMovie in HD.
Three options are currently available from Apple to output video but none of these support HD resolution:iPad Dock Connector to VGA Adapter (1024 x 768 pixels)
Apple Component AV Cable (576p and 480p)
Apple Composite AV Cable (576i and 480i)
We'll post updates here as soon as we get more information on iPhone 4 HD output.