Random Dreamcast tomfoolery for Retrochallenge 2012

This month is Retrochallenge 2012 http://retrochallenge.org/ -
basically "do something with hardware from the last millennium and
tell the world about it"

On the offchance anyone here might find an entry related to the
Dreamcast of any interest, I humbly submit mine :)

http://netbsd0.blogspot.co.uk/2012/07/retrochallenge-2012-public-access.html
http://netbsd0.blogspot.co.uk/2012/07/dream-little-cast-of-me.html

Given the DC can mount a standard io9660 filesystem from a CD in the
gdrom drive it occurs to me that support for the serial port (or some
*cheap* (non BBA) communication device connected to a game port or
similar) could make it much easier to play with NetBSD/dreamcast...

Does anyone know if a maple/serial adaptor is available? (or if the
serial port is exposed as a UART?)