D43 Semi-Slav Showdown (1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6), round-robin, switching sides, 12 games. Houdini 2 Pro, Houdini 1.5a, Deep Rybka 4.1, & Critter 1.2 http://www.powerchessproject.org/live-computer-chess-games
Edit: Critter failed on me half-way through game 1, so the tournament has been restarted with Stockfish 2.1.1 JA x64. My apologies.
Edit: Houdini won this event: http://computer-chess.blogspot.com/2011/10/houdini-20-pro-wins-semi-slav-showdown.html
The Power Chess Project is now broadcasting live computer chess games.
Visit: http://www.powerchessproject.org/live-computer-chess-games to see them.
The engines usually play both sides of an opening. After game 1 finishes, you can click on the drop-down bar to view game 2, 3, 4, etc.