Okay, the Desktop Flickr Organizer works (kind of). It's rather buggy, but if you're daring enough to give it permission to your Flickr photostream, then follow these instructions:
1. Install mono: emerge -av mono
2. Install gtk-sharp: emerge -av gtk-sharp
3. Install gconf-sharp: emerge -av gconf-sharp
There is one more unmet dependency -- not sure if it's an issue or not, but it seems to somewhat work without explicitly merging it above -- that is, sqlite.
Either way, once all the above is done, donwload it from
http://code.google.com/p/dfo/. Extract it to a directory of your choice and run it by: sh run.sh (in a terminal).
The main DFO window will pop up. The first thing you want to do is grant it access to your flickr photostream. To do this, click on the "Flickr" menu, then Connect. It will launch your default browser to a page where you can grant DFO access using the Flickr API. It crashed on mine during this process, but I granted it access anyway, and re-launched it. It started to synchronize everything... tags... sets... etc.