I learned that as recently as yesterday, and it makes alot of sense. Rehnquist would have had alot of confidence in Roberts, and may have even played a roll in getting the ball rolling on the initial announcement several weeks ago. I can remember alot of FReepers had no clue who Roberts was at the time. I know I didn't, beyond being one of the best litigators to enter the halls of the USSC.
But then, I've always been a BIG Rehnquist fan, so perhaps that's why I knew.