This is something myself and quite a few friends are interested in too.
We have a large community wireless network running down here in Hobart,
Tasmania, with approximately 20 sites all linked by various point-to-point
links, we use Linux boxes running the Quagga BGPD at the moment to make life
real easy from a routing point of view, and would love to move to using
m0n0wall for these routers.
A friend managed to get a stripped down version of just RIPD and BGPD from
Quagga running at just under 1mb, now that there is extension support in
m0n0wall, I'm hoping that we can get a extension put together to add BGP
support to m0n0wall.
More info can be found on Quagga at http://www.quagga.net/ for those interested.
The first step is for us to get BGP working on a m0n0wall box without any fancy
web based configuration front end, just using pre-written configuration files.