The card looks nice, but it's clearly for specific applications that use the (as mentioned in the EM url) Total Freedom libraries. I've never heard of that library before, so chances that any common program use it are low. Coprocessors are nice, but software must be aware of them. SIMD are a bigger benefit than this since they need no driver to be used. Thus I choose a G4 anytime over this.
G3s are non SMP-capable, i.e. a kernel cannot provide true support for < 1 processors. It's still possible to have multiple CPUs but they'll become mere "peripherals" or coprocessors that are controlled essentially by a host CPU (in that case, the mac's processor will control the 1-4 processors via pci).
What I'd really like to see is a G3 mac that Apple hasn't intentionally put specs down after Apple's first G4 mac. That I would find awesome 🙁