Brian Candler wrote:
> sudo works fine in Ubuntu. Even if you run from the live CD, you can do 
> "sudo bash" to get a root shell.

or "sudo -i":

  -i [command]
              The -i (simulate initial login) option runs the shell
              specified in the passwd(5) entry of the target user as a
              login shell.  This means that login-specific resource files
              such as .profile or .login will be read by the shell.  If a
              command is specified, it is passed to the shell for
              execution.  Otherwise, an interactive shell is executed.
              sudo attempts to change to that user's home directory
              before running the shell.  It also initializes the
              environment, leaving DISPLAY and TERM unchanged, setting
              HOME, SHELL, USER, LOGNAME, and PATH, as well as the
              contents of /etc/environment on Linux and AIX systems.  All
              other environment variables are removed.

When setting up an ubuntu system, I always used to set up a root 
password (just "sudo passwd root" IIRC), until I found out about the -i 
option. Now I just use that instead.