...This plugin and the "check_backuppc" check sligtly different things, and in different was. You can use both...
Tested on:
BackupPC 3.2.1 / Ubuntu 12.04
Should work in most similar systems i think. Let me know otherwise (create a ticket!).
Installation is easy:
Just put the check-script inyour nagios server, and the other (included) script somewhere so that the check-script can find it (e.g. in the $PATH, or edit the check script for a custom location).