Yes, the cards were made for the Amiga 3000 and 4000 CPU socket. There was a 060 card for the Amiga 2000 as well, but it is very rare. The most sought after CPU upgrade is the Cyberstorm PPC. It has both a PowerPC 604e and 68040 or 68060 CPU on board. Whats neat is that both CPUs could be active at the same time due to the on board memory management system.

http://amiga.resource.cx/exp/cyberstormppc

http://en.wikipedia.org/wiki/PowerUP_%28accelerator%29