Version 0.4 of Gnuk has been released. It implements flash ROM garbage collection. Now, you can make your signature more than thousands times.
Host side program for DfuSe is added. Yes, it is Free Software. Gnuk development can be done with no proprietary OS. JTAG debugger is no longer the requirement.
If you have CQ STARM, just try it. Or else, you can purchase STBee Mini (< JPY2000.-) and enjoy Gnuk.