Vista second OS to fall to hackers in security contest - Ars Technica

After Mac OS X, Vista fell at PWN2OWN. Linux persevered, however...

Microsoft's Internet Explorer team should see this as a great accomplishment considering how poor IE6's security record has been. It looks like Vista's IE7 stood up to the challenge. Nevertheless, Vista's fall on the last day left the Sony Vaio laptop running Ubuntu as the ultimate winner—Linux was the last OS left standing.
Grats to Ubuntu!