The package database pkgdb2 is the place where is managed the permission on the git repositories.
In simple words, it is the place managing the "who is allowed to do what on which package".
For each package, when they are created, the summary, the description and the upstream URL from the spec file are added to the database, which allow us to display the information on the page concerning the package. However, until two weeks ago, this information was never updated. That means that if you had an old package whose description had changed over time, pkgdb would present the one from the time the package was created in the database.
Nowadays, we have a script running on a weekly basis and updating the database. Currently, this script relies on the information provided by yum's metadata on the rawhide repo. This means that packages that are only present in EPEL or that are retired on rawhide but present in F21, will not have their information updated. This is likely something we will fix in the future though.
In the mean-time, you can now enjoy a pkgdb with summary and description information for almost all packages!
As an example, checkout the fedocal page, you can now see a link to the upstream website, a short summary and a little longer description of the project.
Also, to give you a little hint on the amount of updates we did:
The first time we ran the script:
16638 packages checked 15723 packages updated
Last week's run:
16690 packages checked 50 packages updated