Installing rasbian from ubuntu.
  usb-imagewriter is no longer available in the ubuntu repositories (under raring, anway), and has been pulled from a PPA referenced by a community doc.  But that's cool, it's a fairly easy process regardless.

  1. download the image from: http://www.raspberrypi.org/downloads
  2. extract the image: unzip 2013-02-09-wheezy-raspbian.zip
  3. if you've popped your SD card into your card reader, find the mount with df to see what device it is.  In my case, it came up as /dev/sdb
  4. load the image to your SD card: sudo dd if=2013-02-09-wheezy-raspbian.img of=/dev/sdb ... grab a beer; it takes a while.
that's it.  slap that sucker into your pi, and boot it up!