I confirm that IQ tests are forced to be bell curves; at least those using the methodology I learned at university.
Calibrating the test (giving it to many people) returns information like: "50% of test subjects can solve 23 problems of these 50" and "98% of test subjects can solve 41 problems of these 50".
Then the next step is to put these data in the bell curve, saying: "therefore 23/50 means 0 sigma = 100 IQ" and "therefore 41/50 means 2 sigma = 130 IQ".
But you can't assume that this is linear. To explain it simply, let's assume that the more intelligent person always solves a superset of the problems the less intelligent person solved. Therefore, any person with IQ between 100 and 130 would solve all the 23 "easy" problems, some of the 18 "hard" problems, and none of the 9 "impossible" problems. But how many exactly -- that depends on how difficult exactly those "hard" problems are. Maybe they are relatively easy, and a person with IQ 115 will solve all of them; and maybe they are relatively hard, and a person with IQ 115 will solve none of them. But that is a fact about the test, not about the intelligence distribution of the population. Therefore this fact should be removed in the normalization.
A long blog post explains why the author, a feminist, is not comfortable with the rationalist community despite thinking it is "super cool and interesting". It's directed specifically at Yvain, but it's probably general enough to be of some interest here.
http://apophemi.wordpress.com/2014/01/04/why-im-not-on-the-rationalist-masterlist/
I'm not sure if I can summarize this fairly but the main thrust seems to be that we are overly willing to entertain offensive/taboo/hurtful ideas and this drives off many types of people. Here's a quote:
The author perceives a link between LW type open discourse and danger to minority groups. I'm not sure whether that's true or not. Take race. Many LWers are willing to entertain ideas about the existence and possible importance of average group differences in psychological traits. So, maybe LWers are racists. But they're racists who continually obsess over optimizing their philanthropic contributions to African charities. So, maybe not racists in a dangerous way?
An overly rosy view, perhaps, and I don't want to deny the reality of the blogger's experience. Clearly, the person is intelligent and attracted to some aspects of LW discourse while turned off by other aspects.