http://www.nyse.com/about/holidayclosings.html says nothing about an early close on 12/31. Sorry, looks like you gotta trade all day
1:00 pm NASDAQ and NYSE 1:02 pm OneChicago 1:15 pm NQLX and Globex 1:30 pm ACE 3:00 pm Brut 3:30 pm Instinet, Btrade, Arca 5:00 pm Island 11:59 pm Santa's Workshop
Yeah, it is slow now. But just around the closing bell on the day before Thanksgiving, futures suddenly swing 20 points or so. Although stocks did not moved dramatically, options did similiar shocks.