Arduino assembly programming?

So i see linux, windows and mac os x... are bsd systems supported?

Which BSD did you want?
The issue are:

  1. that the usual Arduino talks to the host via USB, and the FTDI chip needs a driver.
  2. The Arduino IDE is built for and bundles platform specific tool chains (e.g. assembler). The Arduino team doesn't bundle up a BSD tool chain (http://arduino.cc/en/Main/Software)

wrt 1. I did a quick google and found this page http://www.ftdichip.com/Drivers/3rdPartyDrivers.htm which may help resolve that problem.

As for 2., Have a look at:
http://www.arduino.cc/playground/FreeBSD/CLI
and
http://www.arduino.cc/playground/OpenBSD/CLI
to understand the state of the toolchains on BSD.

I'd like to echo the suggestion that you might look at:

for low-cost, USB enabled AVRs with Open Source tools.

HTH
GB-)