Since the PCB ID isn't dumped with games, and the ZSNES team isn't interested in them, we get LoROM and HiROM, and have to make every game work. It's also the same reason we're stuck with copier headers and 20+ SNES ROM extensions in 2009.
Nach did an outstanding job and created generic layouts that work for all known games. Not the solution I'd personally want (I want the PCB IDs (or an exact list of mapping info for said PCB), as well as ROM, save RAM and RTC data all stored in the same file), but it works.
For the time being the PCB information could be added to the hashfiles.
Someday I sure would like MESS to get to a "supported software" list like MAME. There just seems to be so many things it could solve. This is a whole nother thread worth of discussion so I don't want to derail the awesome SNES progress here.
PS...someone give byuu svn access. byuu - It is just like helping your neighbor work on his busted hotrod instead of your own.