Its over a week now, and no ethical hacker wants to admit it!
the CanSecWest2008 proved that Linux or more preciesly Ubuntu Linux Configuration (an updated one of course) was hard to crack compared to Vista, and Mac. the problems with the later were mostly client application attacks, however still Linux seems to be a bit harder to bite 

http://www.linux.com/feature/131059

Client application security, web browsing, email, document reading are the main easy traget for system compromise

_Marshel_ ,

the point was that systems, or operating systems especially on the server have far better security than before as a default setting (AV, IDS, antispam, antispyware, personal firewalls, etc).

however client software can open big doors, and through this networks, and trusted servers can be exploited.

the client software that was exploited in Windows vista, and on the MAC can be argued to have similar flaws in Linux, however in Linux you have other layers of defense (local home dir, user account priviliges, apparmor or selinux security domains).

so may be Linux Rocks, however if we are not careful enough we and the day to day client applications we use are the weakest link

Also in the interview with the guy who targeted Vista, and I believe Mac, he said next year he'll target Linux.  His view was that they are really all the same, which is a bit pessimisted compared to my own view... I prefer Linux, but I'd admit there are flaws and bugs for each.  Was rather interesting his trying to sell his laptop that might have 'traces' of his 0-day exploit on it on Ebay.  He appearently wanted to see what a 0-day exploit would go for on the open market, though he claimed by the time the bids finalized, Adobe was supposed to have a patch out for the bug he had found.  Either way, I don't know enough personally about making holes in any OS to comment professionally.