Hello from Arizona!
I'm trying to setup my SD card using these instructions: http://elinux.org/RPi_Easy_SD_Card_Setup, and step 9 scares the hell out of me. Can someone clarify this for me?
"Using the device name of the partition work out the raw device name for the entire disk, by omitting the final "s1" and replacing "disk" with "rdisk" (this is very important: you will lose all data on the hard drive on your computer if you get the wrong device name). Make sure the device name is the name of the whole SD card as described above, not just a partition of it (for example, rdisk3, not rdisk3s1. Similarly you might have another SD drive name/number like rdisk2 or rdisk4, etc. -- recheck by using the df -h command both before & after you insert your SD card reader into your Mac if you have any doubts!):
e.g. /dev/disk3s1 => /dev/rdisk3"