Watch out Wiinja, Cyclowiz, and WiiKey, the creators of the WiiXT have dubbed it the "Ultimate Wii Modchip", and with all the features it purports to have, they may well be right. That is, if it's real. In addition to Wii and GameCube homebrew and backups, apparently the WiiXT also promises region-free DVD playback (wait, huh?), Virtual Console support, stealth operation, recovery mode, and uses 128MB ROM flash memory, 512MB flash storage (presumably for games), and an external USB dongle for enabling and disabling the chip, upgrading, and reflashing. Although there's no proof that this thing exists (or that the Wii can read and play back DVDs, as WiiXT claims), apparently it'll run about $65 should it ever hit the streets. This could be one to keep an eye out for should it emerge from vapor.
[Thanks to everyone who sent this in]