Well, they're dated as "best by" 9 months from when the coffee in them is roasted and packed, just fyi. It won't do any harm to try the older ones, but be prepared for some noticeably stale coffee relative to freshly packed k-cups (opinions differ as to just how noticeable the difference is). Another member, EricBNC, has talked about how flavored coffee seems to age better than unflavored, and I tend to agree with him.
Now you've got me curious about the truly antique 2007 k-cups. Think of it as a science experiment!