If you want to find out from which PPA a specific package was installed or what other PPAs hold it, you can use the following command: (found at superuser.com)
$ apt-cache policy mpd mpd: Installed: 0.16.2+git20110331.6d3ed3f-0ubuntu1~ripps1 Candidate: 0.16.2+git20110331.6d3ed3f-0ubuntu1~ripps1 Version table: *** 0.16.2+git20110331.6d3ed3f-0ubuntu1~ripps1 0 500 http://ppa.launchpad.net/gmpc-trunk/mpd-trunk/ubuntu/ maverick/main amd64 Packages 100 /var/lib/dpkg/status 0.16.1-1ubuntu1 0 500 http://de.archive.ubuntu.com/ubuntu/ natty/universe amd64 Packages
Here you can see that the package
mpg is in the PPA gmpc-trunk/mpd-trunk and also in the natty/universe repository.
The installed version is that from the PPA - also indicated by the