Yes, the iAPX 432's FPU is related to the 8087. I think they took the 8087 design and redid it for the 432, but I haven't been able to nail down the details. I should take a closer look at the dies and see if there is any similarity.
I looked at the iAPX's 432 floating point more closely; it uses the same floating point model (which became IEEE 754), but the hardware is completely different. In particular, the iAPX 432 doesn't have nearly the same hardware support for floating point that the 8087 does. The iAPX 432 uses a 16-bit ALU both for integer and floating-point math, so it's much slower than the 8087's specialized 80-bit datapath. The 432 also doesn't support transcendental functions like the 8087 does; it is much more limited, supporting arithmetic, absolute value, and square root.
