PPA's are released through a site called Launchpad.net
Launchpad is owned by the same company as Ubuntu ... therefore, Launchpad makes PPA specifically for Ubuntu.
No other Linux OS system uses PPAs. Not Debian, Fedora, Slack, Gentoo, or Arch ... although some people have re-configured a PPA or two to work with another OS-system. There are some of the Debian Devs that are also, Ubuntu Devs.
With Ubuntu, when a new version is released, the recommended method to upgrade is to do a 'fresh install'
With Debian the recommended method is not to re-install but to update/upgrade. If you have been keeping up with your regular updates, you already have the new release.
Debian only releases a new version every 2-3 years (when it's ready ... and totally 'bug-free')
Ubuntu releases a new version every 6 months, and an LTS every 18 months - on schedule, regardless if it's ready.
The current version of Debian 6.0 Squeeze is now being released and is more stable and up-to-date than any Linux distribution out there. Imagine releasing a totally 'bug-free' OS ?
Debian is well-known for being rock-solid stable - always. The farther a version of Debian goes after release (if not regularly updated) the more out-of-date most Applications become. You have to keep up and update these yourself. So if you have Debian or LMDE -- keep up with the updates and enjoy a solid, stable OS -- with never a need to re-install.