A lot of websites encourage you (OMG Ubuntu...) to install ppa's but doesn't tell you how to uninstall it. On a default install it's possible to install a ppa by a one-liner but uninstalling isn't a one-liner...
Second: The names of the apt cmd's are strange -> 'apt-add-repository' and 'ppa-purge'. Why not 'apt-add-repository' and 'apt-purge-repository'??? (create an alias could help)
If I'm right, precise will have a 750 MB iso, so they should deffinitly add 'ppa-purge' to the default disc.
Is there a dev that could explain me why 'ppa-purge' is not installed on default Ubuntu 12.04?