From SFGate's business column/blog (http://www.sfgate.com/cgi-bin/blogs/bottomline/detail?entry_id=73787&tsp=1):
Luckoff told to his staff today that he has resigned from his position as President and General Manager of KGO and KSFO Radio, ending his tenure of the past 35 years.
Apart from the 'thanks for the memories,' no explanation immediately forthcoming.