Current World Champs: Part 1
Not necessarily a human champion, but still: a new chess engine has entered the ChessBase stable (garage?), and it's the 2005 champ: Zap!Chess (previously called "ZAPPA", but renamed, I'm guessing, to avoid legal issues with the late musician's estate). Like its stablemates, it's fearfully strong, but it's especially so for multi-processor and 64-bit systems. You can find general info and purchasing information here, and I also recommend taking a look at the dedicated ZAPPA site.