To be blunt, if someone knew of some advantage that was not generally known, why would they post about it online, instead of exploiting it themselves?

QF is no different than other areas of engineering, like programming, where there is some exchange of information about methods between professionals. You can exchange a lot of information without revealing a specific trading strategy. Also there are usually auditors and risk managers that need to understand what is going on in a position and QF provides a language to describe the reasoning behind why a trader has a certain position.

I don't know about that. I read and discuss algorithms in the Wilmott forum. http://www.wilmott.com/index.cfm

There is actually alot of useful traffic that goes on there. Having said that, the Wilmott forum acts more like mathoverflow than stackoverflow in it's non tolerance for basic questions.

The majority of the questions on that first page of proposals have nothing to do with Quantitative finance. Moderating such a forum would be a nightmare.

Perhaps this indicates a market for a separate "Hokey-pokey finance" StackExchange ...

Most of the samples are voted up as "great off-topic example" so I think we don't have too much to worry about.

Presumably those won't be upvoted on a real site.

LaughingStockExchange?

Are you looking at the "newest" questions? or the off-topic questions?

looking at the on topic questions it seems more like a general QF FAQ than a specific Q and A type place.