Nick Matzke has dug into the literature on evolution of chloroquinone resistance in a comment so substantial it ought to be a post on the Panda’s Thumb. This magic number of 1 in 1020 as the probability that a specific two-amino acid change could evolve that Behe uses as his linchpin metric for evolvability throughout his book turns out to not actually describe the probability of a pair of mutually dependent mutations…
So it looks like resistance actually occurs by the gradual accumulation of several mutations, and that what you are seeing in the wild is not a few rare double-mutation events, but instead a few much-evolved strains that have accumulated a large number of resistance mutations.
…and the number itself is of rather shaky provenance.
The evolution of malaria really is the major theme running throughout the book, and it’s looking like he hasn’t gotten any of it right. I wondered how such sloppy scholarship could have passed muster, so I took a look at the acknowledgments page to see who had helped him out. Here’s the roster of great minds:
Lydia and Tim McGrew, Peter and Paul Nelson, George Hunter, David DeWitt, Doug Axe, Bill Dembski, Jonathan Wells, Tony Jelsma, Neil Manson, Jay Richards, and Guillermo Gonzalez read the manuscript, and Bruce Chapman, Steve Meyer, John West, and Rob Crowther provide support.
In other words, his reviewers were the gang of incompetent philosophers, theologians, and creationist ideologues who willingly associate themselves with the Discovery Institute, with nary a real biologist among them. No wonder such bad science could slip into publication.