Does XeTeX work with OpenType fonts?
Yes (at least somewhat)! See the OpenType examples in the Sample Files archive. Note that the appropriate OpenType fonts (not supplied with XeTeX) will be needed to typeset these samples. The OpenType support is a preliminary implementation and I hope to refine it in future versions. If Apple would build in support OpenType layout features at the ATSUI API level, it would be far preferable, and would enable such fonts to work in other applications as well, not only within the XeTeX typesetting engine. I would encourage people to provide feedback to Apple, requesting full support of OpenType layout features in the Mac OS X text APIs.