Yup, I built one last year..haven`t reprogrammed the PIC chip with the latest code yet though , or tried the ATX control stuff that the author designed after I built my adapter.
I found it was easier to solder the interface wires to a PLCC socket and push that over the A1200`s keyboard controller chip instead of soldering directly to it. Doing this also means it`s damn easy to remove the adapter too.
Anyway, it works a treat, haven`t had any problems with it..and it killed a cold winters day building it!