Ubuntu – Any programs to help tag/organize files

I would love a program to help tag and automatically sort files… picture something a lot like a Gmail inbox, where new and unsorted files remain in the inbox, and files can be searched, tagged, etc.

I'm actually considering starting a project like this, but on the long shot something like it exists, I figure I might as well save the time. Is there anything like this, either as a Nautilus extension or a standalone program?

Edit

I just upgraded to 11.04, and it looks like something is in the works with this… if I right-click a file, the context menu has a "Tags…" option which lets me tag files (this is also available in file properties via a "Tags" tab). A handful of my files appear to be automatically tagged, even. …or did this happen when I installed Tracker?

The only problem is, I can't find any way to make use of the tags. Is there a way to search them? Using the Unity search bar doesn't appear to do the job (yet).