This has been all over the blogs and news.
Some samples..
MacBook Air Hacked In Two Minutes, Vista finally falls when Adobe Flash is installed, Ubuntu Beats OSX and Vista in Pwn 2 Own Hackathon
On the third day of the PWN to OWN Contest where three laptops (one Vista, one OSX, one Ubuntu) were exposed to allow experts attempt to ‘break’ or ‘0wn‘ them.
“So at the end of the last day of the contest, only the Sony VAIO laptop running Ubuntu was left standing. “
Nice to see 
2 Comments
I’m not surprised that OSX and Vista both got hacked, but I’m pleasantly surprised that Ubuntu managed to keep the hackers out. And what wonderful timing, coming less than a month before Hardy ships.
With all respect, the street value of a previously unknown 0day networked exploit is over 100 000 euros. No one who is able to produce those will go and practically donate one to a competition with such a measle prize. Especially when it means exposing yourself. The fanboyism’ish pleasure of making one platform look “bad” is really not a big enough motive either.
I am not saying Ubuntu is not bad, please don’t take me wrong. Ubuntu is doing pretty damned well, especially if compared to the OS X. I am just saying that the evidence in hand is not enough to support conclusion that Ubuntu is extremely secure. There is still much to be done, eternally.