I always thought a good line for Canonical to get into would be to release a "Granny-buntu" distro that was super-locked down that grandkids could set up for their elders once and then ideally have a few easily identified launchers on the desktop that would launch with sensible defaults, and nothing else.
An unprivileged account can still do stuff like accidentally hide the toolbar or delete some shortcut to an application. The machine still boots, but it's effectively unusable.
