Replacement FOUND! Rated 4 out of 5 stars

I've been looking for an update to this that works for ff3.6 for so long...and I finally found it.

Show Parent Folder. It is up to date, works great and compatible with FF 3.5-3.7

A nice complement to this is Go To Parent Folder.

FF 3.0-3.7

This user has a previous review of this add-on.