Anna Salamon and I have finished a draft of "Intelligence Explosion: Evidence and Import", under peer review for The Singularity Hypothesis: A Scientific and Philosophical Assessment (forthcoming from Springer).
Your comments are most welcome.
Edit: As of 3/31/2012, the link above now points to a preprint.
I did include Rushton in my research summary, IIRC, but it's probably a good idea to not cite him - Rushton is poison! An editor on Wikipedia tried to get me punished by the Arbcom for citing Rushton, even. (What saved me was being very very careful to not ever mention race in any form and specifically disclaim it.)