According to a Swedish tennis expert, Johan Porsborn, Rafa's loss in Shanghai RR secured Federer's breaking Connors' record of 160 succesive weeks at the #1 spot. The earliest Nadal can surpass Federer on the ranking is the 5th of March 2007, and at that time, Fed will have topped the ranking for 161 consecutive weeks.
Source article (in Swedish): http://www.svd.se/dynamiskt/sport/did_14059090.asp
already posted about it in the Fed forum the day it happened.
Two records that Connors have still remain almost impossible to break: 109 tournament wins and 20 consecutive years as the biggest asshole on tour.