Interesting, I've been getting a similar noise... kind of an intermittent rattling when the car is cold, and idling in neutral with the clutch out. I've also got a bit of clutch chatter, so I'm hoping it's just the throwout bearing and not something that requires cracking open the tranny.
Just finished installing a clutch/transmission in my festiva, so I'm all brushed up on that job! hehe....