Hackers exploited the 3 major browsers on day one of Pwn2Own. As expected, IE8, FireFox and Safari were all penetrated within minutes of the competition starting.
Most impressively, Peter Vreugdenhil, was able to exploit a vulnerability in IE8 on Windows 7 allowing him to bypass the operating systems DEP (Data Execution System) security mechinism designed to stop this sort of attack. Vreugdenhil, a first time Pwn2Own participant, earned a $10,000 prize for his efforts.
The only browser left standing after day one was Google Chrome.