A little while back I put up a brief post about Steve Jones' hypothesis that human evolution is slowing. At the time this proposal was on the receiving end of a fair bit of critical discussion on various science blogs.
Now here's an article by Benjamin Phelan, in Seed magazine, that suggests that the reverse is true - that human evolution is accelerating. (Not in the sense of large-scale morphological changes, but at the level of the genome.) It's quite a lengthy post, but really interesting & easy to read.
And this debate is an excellent example of how science proceeds - by people putting forward hypotheses & data & seeing them critically analysed by others.