I haven't had a rambling technology post in a while, so I thought I'd type one out now as I'm finishing lunch.
3D movies - why haven't they caught on? The first documented 3D movie was in 1922 - five years before The Jazz Singer (the first feature length talkie). They've come and gone, even as technology has improved, but they remain as little more than a novelty. There are a handful of the 3D theaters at Disney World, and usually one or two blockbuster films a year will be released in 3D. I think in the next five to ten years, that will start to change.
1. It's finally reaching a point where 3D movies in the home are accessible to the average consumer. Creative use of DLP processing in rear projection TVs makes this possible. That's been around for a few years now, and it hasn't made a huge difference, but... ->
2. Porn. I'm not joking -
Gizmodo reported on it earlier today. Most major advances in multimedia technology (VHS, DVD, the internet itself) have been pushed further or adopted sooner because of the amount of money in the porn industry. It looks like 3D might be next. (Addendum - there's speculation that the inertia opposing Blu Ray is the porn industry - as high def makes the shoddy production values more obvious).