Nepomuk has long required a convenient way of managing tags. I've previously tried this with a simple Tag Managing Application, but that wasn't something that we wanted to ship. For the KDE Workspace 4.10 release, we are releasing a Nepomuk Tags kioslave.
Nepomuk has always provided users a way to browse tags, but it was only one tag at a time. This seemed fairly limiting. Once could browse by more tags, but then you would have had to write the query yourself.
With this kioslave, you can finally browse the files based on the tags, and then filter the search even more by selecting more tags.