Alongside the unveiling of the iPad 2, Apple has announced a new video mirroring feature.
Using an adapter (sold separately) the iPad will send audio and video to an external display via HDMI. There's also a second 30-pin connector to USB cable so you can charge your iPad while presenting.
Video mirroring and video out can be performed with the Apple Digital AV Adapter or Apple VGA Adapter and supports up to 1080p.
The digital adapter costs $39 and also supports the iPhone 4 and iPod touch (4th generation).