1.8b Development

I've tried this and a few other beta versions to try to realize support for this newer hardware, but they all hang at:

em0: Using an MSI interrupt

Using this motherboard with both onboard NICs enabled: http://www.supermicro.com/products/motherboard/Xeon/C202_C204/X9SCL-F.cfm

Also, some have reported that the shipping bios on that board was buggy; I've tried it with the shipping bios and the recently released 2.0a bios.

http://i.imgur.com/pEcTa.png

A quick google brings up a successful install of pfsense on the same - but it seems to require an AMD64 build. Not sure there is one available for Mono

See...
http://forum.pfsense.org/index.php?topic=44316.0

I have seen that, and can confirm that 32-bit pfsense 2.0.1 hangs at the same place, while 64-bit boots successfully and detects both nics on this motherboard.

Over there I don't see any indication of why this is though, or if it can be overcome in the 32-bit version of either distro?

Are you sure it has hung ?  are you using a serial port ?  If so, try ping the lan interface to rule out that the serial port interrupts are wrong etc.

i386 has ACPI and amd64 doesn't, so handling of interrupt allocation is different.

You can build an amd64 version of m0n0wall, you just run the build scripts on an installed amd64 machine instead of an i386 one.  This isn't in the nightly builds, but I will build one later and post a link for you.