Ok folks, this is a fun one. I just checked in a set of patches from me and Bill that teach PCB how to change the number of layers in a board. The default is still 8, but the default maximum is now set to 16 (easily changed via recompile), and you can add, delete, and move layers.
So you can create a two layer board that actually has just two layers! Or you can add more copper or "special" layers (pcb doesn't treat them any different than before, there's just more of them). Eight layer board with an outline is now possible by default, for example. And you can add internal layers and rearrange them to reflect your stacking order. Also, unlike changing layers in the past, PCB will detect the number of layers in your *.pcb files when they're loaded, so you don't need multiple copies of the pcb binaries to support multiple board sizes. Note that the *.pcb file format hasn't changed; new PCBs can load old files just fine. Old PCBs can load new files as long as they have exactly eight layers. Caveat: don't delete a layer with stuff on it. It won't warn and can't undo all that yet. There's probably some memory leaks in deleting layers too, so if you spend all day deleting layers you might run out of memory ;-) Let us know if you find any bugs.
