more, interesting info...
my iPod classic shows up just fine on the iMac. But the touch will not.
I restored my touch on my MBP. Then plugged it into the iMac, figuring maybe the iMac will see it if it's a brand new device. No go. Still won't see it.
So my MBP sees the touch, iMac won't.
About to reinstall iTunes, but I'm not sure that's the answer, as iTunes sees the Classic just fine.
ugh.