From the Economist‘s Free Exchange blog, on blogging:
[W]e should expect those with strong resumés but lackluster ideas to abstain from extensive blogging, while those whose critical and analytical skills run ahead of the experience and education categories on their CVs should embrace blogging as a means to signal their exceptional fitness. We would expect those with most to gain from blogging to blog more.
Signaling exceptional fitness. That’s what I’m talkin’ about, baby!