i thought the consensus was that FPGAs, while using less electricity, cost significantly more per hash and thus
it would take a severely long time to recoup your investment at this time.
I think the catch here is the cost of development and production. What makes bitcoin super profitable is that it can be executed on multi-use hardware (your average video card).
The beauty of bitcoin too is that it will make ANY investment worth less and less over time. So if someone releases a FPGA that does 1 Ghash/sec and people buy it for $2,000, the difficulty will go up faster making their $2,000 investment less and less valuable dollar for dollar compared to a $200 ATI card.