YouTube in 3D

Looks like YouTube has supported 3D for almost a year already! How to upload your 3D content:

Record two streams with 2 video recording devices, and put the resulting footage side-by-side into one movie (left & right swapped)

Edit your videos tags and add yt3d:enable=true. For widescreen, add yt3d:aspect=16:9 too.

More info here, here, and at this forum post.