Attached is a port for dfu-programmer (http://dfu-programmer.sf.net/). To build it successfully, you'll need to ensure you have r1.8 or newer of /usr/include/stdarg.h installed.
I've tested on amd64 by successfully updating the 8u2 firmware on my Arduino Uno. (I know the ports tree is still locked for new directories; just sending this out in advance.)
dfu-programmer.tar.gz
Description: application/tar-gz