The Flynn effect has many proposed, non mutually-exlusive causes, but an actual secular increase in real brain horsepower is not among the big ones.

http://en.wikipedia.org/wiki/Everything_Bad_Is_Good_for_You

Most of the ancients that people pay attention to these days are ... well-fed

You mean well-fed in the sense of "not starving," but that doesn't imply "well-fed" in the sense of eating a healthy diet. There's reason to think that upper-class Romans would have been even more damaged by lead poisoning than the poor, and there's good evidence that even emperors were deficient in iodine.

Yeah. The raise is not a simple shift of the entire curve.

Though, this resonates with another topic: there's a lot of people today living in conditions vastly inferior to Americans or Europeans of 1910, mostly in Africa, scoring about the same on the IQ tests as western folks from the 1910 supposedly did. I see a plenty of people both accept the Flynn effect (whenever thinking about their superiority to people of the past) and think that said IQ gap is caused by inherently lower abilities (whenever thinking about their superiority to people of other races).

If true then why has it been acting on white Americans post 1960?

Depends what you mean by 'know more math'. In a sense, anybody as fast as you who spent more time studying knows more than you, for how could it be any other way? But that could be because they have more depth in some areas whereas you might have a broader purview. (E.g. you might know more high-level theory about algebraic curves but lose to Newton on a details-oriented question on most cubic curves.)

And there are far more modern people, of which a greater proportion is producing long-lasting informational stuff like quotes/metaphors/articles/books.

I haven't run the number, but I expect there is more total "literally value" (whatever that means) produced, say, last year in fanfiction alone, that in all text written pre- industrial revolution. By orders of magnitude.

For much smaller values of "know", probably. With google at your disposal, all the math is at your fingertips, but that doesn't mean you know how to solve a problem which doesn't come with keywords to search for. Same applies to typical declarative knowledge.