It only needs to tracking the location of the eyes, not their gaze.
http://www.youtube.com/watch?v=OOy-Dnr3xyU&feature=player_detailpage#t=87s

Between 20 feet and infinity, the difference between focus is practically nil.
It may be more of a problem on a smaller screen, though.

Further than 25 ft, focus distance doesn't make much difference, especially at the resolution of most film. That's probably why Snellen eye charts are placed 20 feet away.

For me, I don't think the biggest problem with 3D displays is the stereoscopy, rather all the tricks used to achieve it at a relatively low price. I get eye strain watching a 2D trailer (while wearing 3D glasses) before a 3D movie just because the picture alternates between images for each eye. I think Sony projectors show both images simultaneously, but there are none of those near me.

I actually find red-cyan glasses easier to use for a very short period of time, because the video is smooth, but the color difference leads to worse headaches in the long run. I'll probably be able to handle the 3D on the 3DS.

That's because most of the dialog for that part came out of Mark Zuckerburg's LiveJournal.
http://www.scribd.com/doc/538697/Mark-Zuckerbergs-Online-Diary

They sensationalized the beginning part of the blogging, though. In the movie he didn't use a comment tag, and he went off about cup sizes.

<p><i>8:13pm</i>.<!- - Jessica Alona is a bitch. I need to think of something to make
to take
my mind off her.- - >I need to think of something to occupy my mind. Easy enough
now I just need an idea...

The script for that part was basically taken word-for-word from Mark Zuckerberg's real livejournal page.
The only major change they made was at the beginning of the sequence when he is typing mean things about a girl. <!-- He actually only said one unkind thing, and it was inside an HTML comment -->

The iPad has a higher quality screen than any netbook. (And any notebook under $3500)

All MacBooks have a TN screen.

The iPad, iPhone, iMac and Cinema Display all use IPS.

Khan actually agrees with you. He encourages using the information gathered by the exercises to pair those who are doing well on a concept with those who are struggling. This tutoring lets everyone build character and strengthen knowledge, not just the instructor. If any students are still struggling, the instructor can focus their instruction to just those students and just those topics. They have more time to answer questions because they aren't spending a majority of their time giving passive lectures.

Khan isn't trying to get rid of classrooms, he's trying to improve how they function.

I'm not sure how well this will translate into subjects not related to math, though.

My 8800 went bad. So did the cards of 3 people I know from work.

All 4 of them were fixed by throwing them in an oven for 8 minutes at 385F. More info here:
http://hardforum.com/showthread.php?t=1421792

I don't know if any of the cards were under warranty, that may have been a better method.

I work with Photoshop on a Mac. Can you explain the real world advantages a Xeon CPU with ECC ram will have over a similar i7? How about the base Mac Pro vs a $2500 i7 machine?

I believe most digital theater screens use 2K projectors... more than 90%, based on how many 4k screens are listed on Sony's 4k page . Even IMAX digital just uses two 2k projectors, each projecting the whole image. I'm not sure why.

I just saw that Sony has a system to project two 2k images simultaneously from a 4k projector for 3D movies. I'd like to see a movie on that. I think non-synchronous frames for the left and right eye is what bothers me most about the 3D movies I've seen.

If all helium balloons float to the sun, where does the sun fly off to?

Yes. The colors are just a lot less saturated when not using a backlight.

The aperture of the human pupil is quite small, so the difference in focusing between 20ft and infinity is probably negligible. (If you focus your eyes on something extremely far away and look at something 20ft away, it won't look very blurry) On screen that is closer to you, such as with the 3DS, this may be a bigger issue, but the small size of the screen may help.

I find that the workarounds needed to display 3D are more annoying that the 3D effect itself. Putting on polarized stereoscopic glasses to watch a 2D movie trailer has many of the visual annoyances that the 3D feature has.