Analyzing decklists from Rounds 1-4 in this tournament is like looking at the results of an Italian election: because it's so diverse and different, no one archetype is truly dominant over all the others; however, green/red still has a big enough percentage of the vote to win lots of games today in every single seat.
Seat A Decklist Breakdown
As you can see, green/red's the most popular of all the archetypes, followed closely by pretty much anything with black in it. It's interesting to note that of the seven single-colored decks played in Seat A, the only white one was piloted by Mike Pustilnik. I had the privilege of watching his feature match, and saw his deck filled with Clerics and Soldiers put up a valiant effort.
Seat B Decklist Breakdown:
Green/red retains its dominance in this seat, but it still doesn't have a clear majority. It's interesting to note that people in the B seat seem to prefer playing with black/white and blue/red more than those sitting in the A seat.
Except for the guy at the end. I don't know what he was thinking, exactly.
Seat C Decklist Breakdown:
In Seat C, even though green/red is still popular, the other colors don't show nearly as much conformity. Seat C seems to be where everything gets thrown together and played more haphazardly than any other seat, and it shows when you look at the deck breakdowns.