Renyi Liu and Howard Ochman describe in the Proceedings of the National Academy of Sciences a series of gene duplication and divergence events that could have been responsible for evolution of the core proteins in the bacterial flagellum (source). The bacterial flagellum has been on of the intelligent design creationists favorite examples of “irreducible complexity” or “specified complexity,” the sort of complex structure whose existence is said to provide evidence for an intelligent designer.
As an evolutionary biologist, I would be delighted to learn that an important piece of this puzzle has been solved. It would be yet another example of how invoking “intelligent design” doesn't explain anything at all, and it would be a nice, large nail in the coffin of those who argue for the intelligent design hypothesis.
Unfortunately, my delight is a bit mixed. Nick Matzke argues that there are some serious flaws in the paper (source). This topic is too far removed from my expertise and I haven't read the Liu and Ochman paper carefully enough for me to feel confident in assessing his critiques. I'm not going to try to judge either the paper or Matzke's critique.
But I do want to point out that Matzke's critique illustrates what makes evolutionary biology a science. Liu and Ochman present data and analyses if favor of their hypothesis – that “core components of the bacterial flagellum originated through the successive duplication and modification of a few, or perhaps even a single, precursor gene” –, and Matzke disputes their hypothesis by bringing different data and different interpretations to the table. Ultimately, the dispute will be settled by further analyses and new data. This dispute illustrates the process of successive refinement through which scientific knowledge accumulates.
When was the last time you heard Dembski argue with one of Behe's intelligent design hypotheses and use data to settle the disagreement? Never, you say? Not surprising. Intelligent design creationism isn't a plausible scientific hypothesis.