Using XeLaTeX on OS X 10.6 (texlive installed with MacPorts) I'm not getting any ligatures with Hoefler.
Example code:
\documentclass[10pt]{article}
\usepackage{fontspec,xltxtra}
\setromanfont[Mapping=tex-text]{Hoefler Text}
\begin{document}
ff fl fi ffl ffi
\end{document}
Gives:
From my understanding Hoefler ought to have ligatures, but they're not showing up. Am I missing something?