Creating a bootable Linux USB disk on Mac

hdiutil convert -format UDRW -o ~/path/to/new.img ~/path/to/source.iso

Open Disk Utility. Right click the drive and click Information, then note the drive path (disk1 or disk2 for example)
Right click the Disk and click Unmount
Back in terminal:

sudo su root
dd if=/path/to/new.img of=/dev/rDISKNUMBER bs=1m

July 8, 2011 — Where DISKNUMBER = disk1 or disk2 for example. Add that leading "r".

Back in Disk Utility, unmount/eject the disk.

Done!