Okay well the article about this study in the New York Times seems pretty fascinating. Apparently, researchers at the Centre for Addiction and Mental Health in Toronto have called bisexuality into question, arguing instead that bisexuals are just gays who aren't ready to come out. I think plenty of us have known gays who went through a "bi phase", so it's somewhat convincing. Also, Claire works at the Centre, so we know they're good people.
But, I'm not convinced that this study has really proven that much, or that it has "called true bisexuality into question". The first qualification is that it hasn't called female bisexuality into question, as women who claim to be bisexual become aroused when they see all-male and all-female porn. Secondly, the group studied included only 33 men who claimed to be bisexual, which is just ridiculously low; at least 1,000 would be the norm. Thirdly, the group was drawn from men who took out personals ads looking for men to have sex with. This isn't exactly the "general population" nor is geographically diverse. Fourthly, there was no control group. Fifthly, how can you atomize human sexuality and reduce it to arousal at a porn video? Sixthly, there's something perverse about judging the entirety of human sexuality through the plethysmograph reading.
Lastly, why would the NYT publish such a lousy study and claim that it calls Kinsey and Freud into question?