Just found this announcment:
pwn2own-Contest 2011As for Chrome, the contest will be a two-part one. On day 1, Google will offer $20,000 USD and the CR-48{Prize: computer with ChromeOS} if a contestant can pop the browser and escape the sandbox using vulnerabilities purely present in Google-written code.
If competitors are unsuccessful, on day 2 and 3 the ZDI{ Zero Day Initiative - organizer of the event} will offer $10,000 USD for a sandbox escape in non-Google code and Google will offer $10,000 USD for the Chrome bug. Either way, plugins other than the built-in PDF support are out of scope.
Nobody was able to hack Google's Chrome in the last 2 annual tournaments...
regards
Torsten