Google::OAuth was published to CPAN on April 20, 2013.
Current release, as of 5.21.2013, is 0.04, and I am using this module in several production websites. As soon as another user can confirm its seaworthiness, I will promote this distro to 1.0 so it's no longer a beta release.
The current release includes Facebook/OAuth.pm. This release is a bit of an accomplishment, since it establishes Google::OAuth as a general purpose interface for webservices. I don't know if there's more demand for a Facebook solution than a Google solution, or whether this module would attract more attention if it were repackaged.
At the recommendation of Perlmonks, I've uploaded the distro to github in order to improve exposure. Github seems more suited for collaboration than a repository, and I'm still no expert.