I really hope people don't turn this into a "Louis CK did it, so you should publish without DRM!". I agree with the anti-drm sentiment a lot of people hold, but this experiment only worked because it's "rare". Every time something like this is done people use it as evidence of the viability of the idea (Radiohead's pay what you want comes to mind too) and that really shouldn't be done. The only reason I heard about this experiment was because it's an experiment and I would personally bet that if this wasn't an experiment a huge portion of these sales would never have happened, I hope in the ensuing celebration of the success of this people don't forget this important fact.

"Louis CK published without DRM and made $500,000 sales in 4 days, therefore if you publish without DRM you too will break your own sales records"