The new website now contains less content; noticeably the DCPU-16 spec is missing. Looks like he's in the middle of retooling. There is a video demo though.
Notch has been releasing quite a few gameplay clips recently. The best place to catch them is http://reddit.com/r/0x10c -- he often frequents the forum.
The spec on the website was awfully outdated, and enthusiasts were already following (and participating) its evolution on reddit, so that's not much of a loss.
