I'm not sure when the 24-clock began ticking with Expedia, however I just stumbled onto their 24-hour 70% off sale at the San Francisco Fairmont Hotel. My original search dates were July 2-July 6, 2008. After the 70% off discovery, I searched some random dates on May, June and July. Many, but not all dates displayed the 70% off sale fare. I wound up booking the Tower Suite for two nights in June -- everything went through perfectly, including obtaining a Fairmont reservation number (aside from the Expedia itinerary number).

An example of the room rates and sale prices:

Fairmont Room -- $399 selling for $120
Exterior Room -- $429 for $129
Deluxe View -- $469 for $141
Signature Bay View - $519 for $156
Main Bldg Suite - $669 for $201
Tower Suite - $869 for $261

Rate vary by dates. Good luck all!