Download
Official Release
Releases are packged in either a BZip'd Tarball or a standard Zip file. Generally Linux users would grab the Tarball and Windows users would grab the Zip, however both archives are identical.
After downloading, you might want to check out the installation documentation.
Distribution Packages
KateOS: Add http://kate.opsat.net/pkg to your repository file (manually or with Realm) and you will have access to the pgid3 package via Updateos or KatePKG.
SVN Repository
It is possible to get v2.1 directly from SVN, like so:
svn checkout http://bobmajdakjr.googlecode.com/svn/tags/pgid3-2.1 pgid3-2.1
Just like any code repository, this contains the latest code I have commited. Even though I attempt to commit only when at a known happy point, it could be broken. I suggest using an official release unless you know what you are doing.
svn checkout http://bobmajdakjr.googlecode.com/svn/trunk/pgid3 pgid3