This is a good example of the kind of thing that can be fruitfully submitted to the lazyweb. But I don't think it's a good example of "collective intelligence", if we have in mind the most meaningful notion of intelligence. The crowd can not find deeply creative solutions to any problem, or create anything or remarkable and original beauty. Only individual humans can do that.
As others have stated, this is a slight misappropriation of the term 'collective intelligence'. In my opinion, collective intelligence has more to do with human beings utilizing each other's efforts by collaborating in an open space and on a grand scale. This is one of the most revolutionary aspects of the Internet and contributes quite a bit to my belief that, in a similar way to the printing press, the Internet has sparked a renaissance that we are all currently experiencing.
Collective intelligence is the slow homing in on a fact or figure you get when a group of knowledgable people bounce the result of their experience off one another.
Your example has little to do with that - it's more a case of getting the right answer if you ask enough people.
There is nothing collective about this. One (or a few) individuals knew the answer, and everyone else contributed nothing.
It goes beyond those who read the post. Some people asked their friends on Twitter and came back with an answer. Others found the information on crowd sourced websites.