It doesn't seem to be on most unsafe lists (or any safe lists)... however, I did find it on one, as well as a couple other sources suggesting the oils in the leaves are unsafe.
I feel pretty bad now that I didn't even think to check when I ordered fresh eucalyptus leaves and branches for my sugar gliders! Nala and Gaz got some of the larger branches (but no leaves) and were fine... but in retrospect, I shouldn't have risked it. It seems eucalyptus is an evergreen, and those kinds of trees tend to be unsafe as a general rule.