my solution for tagging files in ubuntu version 7.10 is the following:
first you have to install the python-nautilus package:
sudo aptitude install python-nautilus
then you have to download “tags-tab”-extension ( http://svn.gnome.org/svn/tracker/trunk/python/nautilus/tracker-tags-tab.py )and move it to .nautilus/python-extensions, and you should make the .py and .pyc files executable, without that it didnt work.
then restart Nautilus:
Alt+F2 and type in killall nautilus
now you can start tagging files and folders. Simply right-click on the item you want to tag, go to the “Tag”-tap and insert your tags.
now you can setup searchfolders, go to nautilus click on the search button and type:
tag:[tagname]
Then go to File->Save search