The result is from 2008, but it's new to me. Abstract:

A meta-study of repeated prisoner’s dilemma experiments run at numerous universities suggests that students cooperate 5% to 8% more often for every 100 point increase in the school’s average SAT score.

Some obvious points from my first five minutes of thinking about it:

• Meta-study or not, the sample still only covers humans. No implications for Friendly AI or intelligent aliens, which don't have our motivations.
• Even among humans the sample is WEIRD, and a subset of WEIRD at that; although there is obviously variation between universities, it's smaller than what you'd get if you extended the sample down into the working class. I also wonder what would happen if the PD was played between students and non-students. 
• Probably a point in favour of the Machiavellian intelligence hypothesis, in that we see those of higher intelligence doing better on a social problem.
• Presumably this implies that your best move, whatever your level of intelligence, is to surround yourself with the smartest people you can find, and then cooperate to ensure they don't throw you out.
• I'd like to know some details: Does intelligence also correlate with effective retaliation? With probing for suckers? What about cooperation in single games? (The study mentions one, in a footnote, which apparently did find higher intelligence correlated with greater cooperation even in one-shot games; but there's no metastudy.)