I've never worried a whole lot about a D&D Intelligence score translating to an IQ score, for a few different reasons.
It's unfortunate, but the relative success of a character is really dependant on the intelligence of the player, not the character. Sure, a smart player can 'play dumb,' but having a high Intelligence score is no more a guarantee of success than having a high Strength or Constitution score. A character's relative Intelligence won't help him if the player decides that it's a good idea to try the mysterious sparkly liquid in the chalice on the evil altar. Besides, in real life, "smart" people do "stupid" things all the time. Things like losing their keys, forgetting to check the oil in their car, or not checking their bank account before writing a check at the end of the month.
The other big reason I don't really worry about defining D&D Intelligence in real-world terms is because there's still no consensus on exactly what intelligence is. Statistical comparisons of D&D Intelligence scores to IQ tests aside, we still haven't reached a verifiable method of determing what intelligence is- much less how to measure it.
I think it's perfectly fine to treat the Intelligence score as it's designed to be: an abstraction. Although we have the hardness and hit points for a one-inch thick piece of iron or wood in D&D, nobody wants to go out and bang at one to figure out how much applied force a "real hit point" is. The same logic applies to me.