What are FPGA's?

[frozenkai]

What are FPGA miners?

[John (John K.)]

http://en.wikipedia.org/wiki/Field-programmable_gate_array

[Portnoy]

http://en.wikipedia.org/wiki/Field-programmable_gate_array

And here I always thought it stood for, "Florida Pygmy Goat Association."   

[goxed]

What are FPGA miners?

I found this online. Some guy who uses fpga for some computing problems. There is a nice analogy with pictures on what is FPGA. This same chip can be used for hashing and thus mining.
http://gradworks.umi.com/3341851.pdf

[J.harris]

The advantage is lower power consumption by multitudes with in turn doesn't generate as much heat.  So if the power bill is troubling you and you don't mind a higher initial investment, FPGA miners may be for you.

$1000 will get you about 800mhash/s
https://bitcointalk.org/index.php?topic=79637.0

[macavity]

A CPU basically loads instructions and data, then applies these instructions to the data. It can do almost any kind of computations. A GPU is a simplified CPU, but thousands of them (not quite accurate, but it works).

What an FPGA does is load only the data. The instructions are already burned in. This allows them to work on the data much, much faster and with less power consumption, but they can only do what they were programmed to, unlike the CPU which can load any kind of instructions. Yes, FPGAs can be re-burned, but that is a far cry from the versatility of CPUs still.