Either WN changed the time, or I miscalculated. The offer will go live at 11:03A EDT/8:03A PDT (three minutes after the announcement headline disappears) with the headline:
We are celebrating 37 years of flying! Grab these low fares before time runs out. Do not worry, there are more to come. Click here to purchase by 10:40 AM CDT, June 18, 2008.
It looks like there will be multiple offers today!