porting regular software to FPGA's is certainly an interesting idea and many people have worked on it (google C to FPGA). Unfortunately, these solutions aren't

porting regular software to FPGA's is certainly an interesting idea and many people have worked on it (google C to FPGA). Unfortunately, these solutions aren't quite what you would think, because the programming model of a microprocessor (serial execution of instructions) is very different from that of an FPGA (parallel evaluation of gates, non-uniform state access/routing -- you cannot just access any variable in Verilog anywhere, you have to make sure it is possible to efficiently lay out your algorithm on a 2D structure of gates). As for JIT-ing, compilation times for FPGAs are often in the hours, and the software involved is unfortunately proprietary (and not easily integrated with). There are some field-reconfiguration libraries, but I am not sure to what extent real-world applications compile new Verilog on the fly..