Did the Jeopardy! website just give away the final contestants before the semifinals even began? I looks like they did, even if it isn't that obvious. Earlier today I got on the Jeopardy! website to the main page for the tournament and under a big picture of all the contestants is a Flash animation of "Tonight's Contestants". But then clicking "Contestant Line-Up" on the menu shows who is playing which night of the semifinals for the next three days and tonight's line-up is different from the main page, save one contestant. "Tonight's Contestants" are each playing on a separate night of the three semifinal games.
After watching this evenings episode, it was definitely the "Contestant Line-Up" page that was correct. That got me thinking that "Tonight's Contestants" were actually the finalists. So I opened up the page source and looked at the filename for the Flash animation and sure enough it's called contestant_plug_day9-10.swf it actually says day 9 through 10 which is the two-game finals match in the 10 day tournament! Oops.