USB Fever has released the HDMI Dongle (http://www.usbfever.com/index_eproduct_view.php?products_id=2076 ) for the iPad, iPhone 4 and fourth generation iPod touch.
The US$69.99 dongle lets you transmit the video and audio on your iOS device to an HDTV or HDMI AV device. It’s plug and play. No external power supply is required, and you don’t have to jailbreak your Apple device.