If you want a dense, technical explanation, I wrote about this hypothetically back in April, for the same site:
http://uploadvr.com/what-the-bleep-is-lytro-doing-in-vr/
The editor informs me that HN has crushed his site, though. Should be back up soon, I hope. (Good argument for mirroring my own articles on my otherwise-defunct blog, I suppose.)