Apple has provided an iPhone 4 and iPad can be connected to an external display via HDMI
Along with the iPad 2, Apple released a new Digital AV Adapter adapter, allowing you to connect iPhone 4, iPod touch fourth generation and iPad to an external display via HDMI to view HD-video in 720p resolution, and in the case of iPad 2 also use mirror image function resolution up to 1080p.
Digital AV Adapter connects to a standard dock connector. On its reverse side - HDMI connectors and replicator docking connector, allowing you to plug the charger while watching a video on an external display.
When connected to the screen image can be displayed with a resolution of 1080p new iPad 2 on the external display (even though viewing the video is still available only in 720p resolution).
Prior to the release of the new iPad adapter, iPhone 4 and iPod touch fourth generation supported only analog video output VGA, and he is no sound, even though Apple TV release on the same hardware platform has demonstrated that all opportunities for HDMI her (platforms) are available.
Cost Digital AV Adapter to the United States - $ 39.