The Nintendo 3DS seems like it's in this vein too— a lenticular display coupled to gyros and eye-tracking.

Does these holograms work for more than one viewer at once?

Where the 3DS is lenticular, these are real laser-formed holograms, and can be seen by multiple viewers without any headset or other gear. Right now view zone is 45 degrees.

Huh, very cool— is it totally passive then, once "printed"? It seems like you're encoding into each pixel what it would have to be for every possible view angle, and I'm having trouble getting my head around how this works.

Hogels record the intensity and direction of the light (giving the ability to "look around" the hologram object).

Yes, this hogel information is permanently exposed onto the hologram film.

So, the holograms are made of "pixels" that look different from different angles? If so, how much crosstalk is it, and how many discrete angles are we talking? Very cool!

Currently a 45 degree view zone with 23 separate view zone images, so about every 2 degrees. Very little crosstalk.