I was waiting for the ubuntu updates to deliver me the Firefox 8 updates but today it delivered me with Firefox 9 when it is not even released by Mozilla ? Am I having beta update PPA ? How can I know that ?
if you go to ubuntu software center and click edit, then software sources, it will list all your PPAs, if you do have a beta PPA you can remove it, uninstall firefox, then reload the PPA's to reinstall the version in the ubuntu repos
if you need better control of your PPAs you can install Y PPA manager, its great to manage PPAs