I've been thinking about this a couple of days. A study published in Psychological Science looked at 445 kids in Connecticut over 12 years, testing their reading ability and IQ once a year. They found that for non-dyslexic kids, higher IQ and better reading ability went together. For dyslexic kids, they did not.
My first reaction to this was that it's nothing new. We've known for years that dyslexia (at least in the old sense of having any of a number of problems processing words visually or aurally, rather than the sense of anybody more reading than 2 years below grade level) is not related to intelligence.
My second reaction is that neither is it new nor should it be surprising. It's just another example of the fact that intelligence (in the broad sense of all mental abilities) is made up of thousands, maybe tens of thousands, of discreet mental abilities. Which ones a particular person has is a combination of genes and accident. My eldest is a whiz at calculus but slow at in-the-head arithmetic.
And dyslexia is such a handicap to overcome that those who become successful in spite of it are probably smarter than the rest of us.