Well, this may come as a slight dissapointment to some folks here, but the Munchausen cart isn't going to have 100% MMC1 support. (as I mentioned in the first place, I believe) Some functionality of the MMC1 is most definitely going to need to be dedicated to controlling the write enable lines for the Flash and RAM chips, which means some control lines will be re-purposed. Alot will remain, but programmers who want to use the MMC1 in the Munchausen will have to work around the missing registers. It just isn't possible to manage the Flash chip without doing this (or increasing the component count, thus increasing price.) A future revision may be able to fully support MMC1 properly, but at this point the first revision cannot. We will try to provide documentation detailing which registers have been changed so that developers can tell if their code will still work or can be modified to work.
However, some good news: the prototyping has begun in earnest as I rip some donors boards apart today, and Blargg thinks we ought to be able to support a multi-cart menu interface for NROM games. Blargg has got a new version of the controller-port cable working correctly as well, using a Poviant USB to serial port adapter, which is super cheap, and I'll be following suit as soon as my parts come in.