The last updates to Italian were made by SourceForge user "sali40" in July of last year. Look in the "patches" section around that date.
You should be able to contact this user (I don't know the gender) at: sali40 at users dot sourceforge dot net
You can work on the language files without first becoming a member of the project. Simply work on the language files. When you're ready with a file, post it in the "patches" section and update this post mith a notification that you've done so.
You don't need to post all of the files at once.
If you wish, I can provide you with a set of Italian files for the SVN version of PGV (we call this version 4.3) where the places that need translating are clearly identified. Just send me an e-mail: gkroll at keldine dot ca