I don't care. And I don't think you should, either.
From the story, quoting Kris Lamb, operations manager of X-Force Research and Development for IBM Internet Security Systems:
It's not that the bad guys never use zero-days. "But it's how they can use a bunch of exploits to get the most coverage [and success]," Lamb says. "It's less about spending resources on [finding] that zero-day."
He's talking about how attackers are finding it more productive to use known exploits, and that it doesn't pay for them to have to dig through software to find yet-to-be uncovered flaws to exploit for attack.
The takeaway from that trend is this: not enough people are patching. If more people patched, the attackers would be forced to find and use zero-days. That would raise their cost of doing business. And that would be a good thing.
But the important thing to note is that you already have to assume that any networked computer is constantly under assault. And the fact is that if it's attached to the Internet: it is.
And you need to assume that your custom-developed and over-the-shelf software is littered with security holes. It probably is.
That's why you should ignore all of the zero-day exploit talk. Because you have to secure your systems as if you already have zero-day vulnerabilities and that the attackers already know about them.
I'll say this again: You have to secure your systems as if you're always under assault from zero-day attacks.
Because too many days of the year, this condition is probably true.
And that's why zero-day talk is nothing but hot air.
Patch the known flaws. Monitor your traffic for anomalies. Protect yourself as if you are always under assault. And call it a day. So ignore all of the blather about what constitutes a zero-day, or if publically disclosed vulnerabilities slipped 5.4% year over year. Who cares?
And if you want to focus extra attention somewhere, direct your attention to hardening your end point applications, and your Web applications. That's where the action is.