I lent it to a friend who wanted to test drive it before buying. He plugged a Shuffle into it and it worked for the first; blew a fuse on the second day. Gave it back to me and I changed the fuse and plugged it into my cig lighter (fortunately without a USB stick - so it turns out).
The radio "thwup"-ed once as the carrier came and went, and the fuse blew again. I can figure it's shat the sheets. :)
Thinking about it: since the Shuffle recharges thru the USB port, and USB is 5v while the car is 12v, I'm wondering if the recharge current killed the voltage regulator... An autopsy is scheduled for next week (I'm vacationing this week).