Cat Shot...or Not?

My '99 2.2L Sonoma -- 96K miles -- has developed a rattling in the exhaust. I put it up on stands and listened to it and, sure enough, its coming from inside the catalytic converter. After it cooled off I shook it by hand -- theres the sound of something rattling around loose in there. Doesn't sound like a lot of small parts rattling (not the proverbial bb's in a beer can) but just one part that's loose/broken/whatever. I've got a California smog test coming up in March. Should I now assume that this truck will spew emissions out the pipe and fail the test because of this? I better start saving up now, if that's the case.