Google's Pwnium challenge followed a familiar pattern in its first two years, with white hat hackers invariably finding a Chrome vulnerability and prompting a round of patches that ultimately made the software stronger. For the Chrome OS-focused Pwnium 3, there's been a slight hiccup: there were no hacks to patch. Despite Google offering a total of $3.14159 million in bounties, entrants couldn't demonstrate a working exploit on the Series 5 550 target machine. That may be a testament to Google's steady security improvements, but it doesn't help discover what holes are left. We'd add that few were left unscathed at the Pwn2Own competition running in tandem -- the regular Chrome browser, Firefox and Internet Explorer all came tumbling down, and Safari may have escaped only because contestants didn't register in advance. Even so, the Chrome OS results may have Chromebook Pixel owners feeling better about their purchases.