I think it is an interesting idea.
I am not sure how well researchers have linked latent inhibition scores to actual chemical states in the brain, but the fact that there is some biology linking to psychological constructs is something that makes the theory more credible to me.
If nothing else, they are searching for something
physical.
Also more details on the Harvard Study:
Harvard Gazette: Creativity tied to mental illness
http://www.nidsci.org/pdf/carson-peterson-higgins.pdf (pdf)