HP Mini 311
First a Zune, then a tiny Blu-Ray player, and now this - a netbook.
Normally a netbook would be terrible for high definition video playback. The Atom processors found in netbooks are usually paired with Intel integrated video, which simply isn't capable of playing high definition video at an acceptable framerate. Even if playback was possible, most netbooks only have VGA-out, which isn't optimal for use with modern HDTVs.
The Mini 311, however, is different. It uses Nvidia's Ion chipset, which is far more graphically powerful than what Intel can offer. As a result, it is capable of high definition video playback both on its own 1024 x 600 screen or on an HDTV. HP knows that, as well, and has placed an HDMI out put on the device to make connection to an HDTV easy.
Of course, the Mini 311 can't play discs because it has no optical drive. But with full wireless Internet capabilities, the Mini 311 can be used with any number of online video services capable of streaming HD video. The Mini 311 will also play any HD video which has been downloaded from online stores. That makes it quite versatile. The price is right, too - at $399, the Mini 311 is only a little more expensive than a Zune HD with an AV Dock, and it is of course a netbook in addition to an mobile HD video player.