There's no denying Linux is more secure than perpetually-patching Windows, but the past month or so has not provided an ideal demonstration.
In August, we saw the arrival of a long-overdue fix for a kernel bug that was six years old; now, in the last week or so, it's been not one but two root exploits causing a fuss.
"Running 64-bit Linux? Haven't updated yet? You're probably being rooted as I type this," was the introduction on Slashdot to CVE-2010-3081, the second such vulnerability to come to light in recent days.
Preceding it by just a few of those days, of course, was CVE-2010-3301, which had actually been discovered and fixed back in 2007 before the patch was inexplicably removed again the very next year, reintroducing the vulnerability.
Put it all together, and you'll see why more than a few Linux bloggers have been scratching their heads about security.