Hmm, I remember some time ago reading someone's blog about running a PowerPC 604 zif from some various IBM PowerPC workstation (RS/6000 series or something another) in the slot in a Beige G3. He was successful but performance was not that impressive (no way to get L2 cache on there). I never heard anything else.
So, I was wondering if anyone has ever tried to do so on a Powermac with a ZIF-riser upgrade card installed (in order to use the L2 cache on the motherboard). I myself have searched to get a hold of the chip itself but it seems to always just be included with whole motherboard (usually $200+ for a good 375MHz or so chip). I can't possibly be the only one that found that mildly interesting.