Glenn Reynolds linked to this Freeman Dyson interview. Dyson seemed to be particularly excited about something called HAR1. This is a small patch of human DNA that has experienced significant evolution since the human and chimp species diverged from their common ancestor six million years ago. Dyson doesn't mention there are 48 other DNA regions that have also changed in the last six million years, just not as much as HAR1.
The research team that discovered the region don't know yet what that particular patch of DNA actually does. But it seems to be related to brain development.