The RPS post also mentioned that the sale is extended until Sunday, October 25.

Cool, I'm glad that I found out just in time to be part of this. I payed $7 for my copy.
The most interesting result of the experiment is the spike in Steam sales. That has significant implications.

Yeah I noticed that and briefly thought I might be able to get it but then I looked and I won't have cash again until the 30th. No drama really, might grab it anyway one day when cash isn't so tight

Correction: most people did pay more than $0.01US, even if that was the most common price paid.
("most people only paid mere 1 cent" would mean that they were more than 50% of everyone buying the game in that week)
Quite interesting is the 391 people that payed $20 or above.

What a way to make money huh?

I agree that the concurrent spike in sales was quite interesting. I predicted earlier in the thread that the exposure the game got as a result of this offer would cause a spike in future sales, but I didn't expect that spike to be concurrent with this sale. The best explanation I can come up with is that a significant number of people were of the mind that getting the game through their preferred distributor (Steam) was worth the price difference between the Steam version and whatever they would have chosen to pay for the game.
It's also nice to see that the folks at 2DBoy are viewing this as the smashing success that it is, seeing as they chose to extend the sale another week.

I think it's pretty cool that some chose to pay more than what the game is normally worth. That speaks volumes about how great that game is, and how an indie developer can win the hearts of many.

Also, it may help increase sales of their next game (if there is one)
People will recognize the name 2DBoy and remember that they let them buy World of Goo at any price they wanted. So they may go out and buy the next game because they enjoyed WoG.
But it may have the adverse affect of having people wait a year and hoping to have another sale like this.

Paid a cent for it, think I got a good deal.

Wow, that's quite a chunk of change they made... Hopefully others will follow in their footsteps!

it's a shame they didn't make any cash on all the people who paid less than 30 cents.
I wonder what would have happened if they'd set the minimum as $1. Personally I'd expect that most of the people who paid 1 cent would have paid $1, and they'd have made an extra $7000. Maybe.
Of course, it's worth noting that one reason it was so successful was that it was unusual, and therefore garnered a lot of publicity. If everyone does it, there will be a law of diminishing returns.

Here are some charts about the experimentation :

Wait, what? So Linux users pay more on average than Mac and Windows users? So unlike them to actually PAY for things.

No, they pay for things that they believe are worth paying for, using Linux because they don't want to pay for Windows but don't think it's right to pirate it. Windows users more often than not pirate software, including their OS, because they just want stuff for free, or at least as cheap as possible.