There is a wonderful interview with Intuit founder Scott Cook. Scott describes how he learned to hire talented A-players. He was looking for four key attributes:

• Intelligence
• Learning ability
• Cares about quality work and satisfying customers
• Gets things done

Scott would ask the candidate's references to rank the candidate on their performance on a scale of 1 to 10. Most responded with a rank of 7. Then Scott would ask the references what was keeping the candidate from being a 9 or a 10. He got the best information at that point. He would ask the reference for another person to interview about the candidate. He would also ask how effective the candidate was at getting things done.