The design side is easy for our very able team. To give you an idea the design, and first proto was built, of Merrick1 in 8 weeks. That's 100X the complexity of what we are doing on this first Bitcoin product. I could give a very long list of similar examples of other projects. This is a professional design and manufacture team that's at the top of profession teams.
We will look at FPGA optimisations and software aspects but I won't promise any timelines. That's part of the reason for the current price. You will have to do a bit of work yourself so this may not be for everyone in this raw form. The timelines on this will depend on what else the design team end up doing. The team is rarely underloaded so this sort thing can take time.
yohan,
some rough edges are not a problem as long as the board has its FPGA bitstream and there is a description of the protocol used to communicate with onboard FPGAs so that mining programs can be upgraded to use your boards.
if, on the other hand, you're selling a "naked" board, without any software nor FPGA bitstream, then this should be clearly stated since very few here will be able to use them even adding a lot of work
spiccioli.
If it is based on a XC6SLX150, shouldn't we be able to use the one of the many bitstreams for various boards out there? So long as we have an interface to program the FPGA it should be smooth sailing? I own no FPGAs but as you say this is a critical issue.
Also, could you guys use a through-hole mounting system for the heatsinks. Something in a similar manner to most other FPGAs. It makes mounting various heatsinks much easier than clip-on heatsinks. Depending on the design, I might attempt to mill a waterblock for these and a through-hole mounting system is far superior than clips.
Is it possible to handle all four FPGAs with one USB Port like the Ztex quad. Icarus and X6500 uses also only 1 port for 2 FPGAs. Would prevent some wire tangle 
