"ZW" == Zdenek Wagner writes:
ZW> CZ/SK hyphenation works both in xelatex and (pdf)latex in T1. I am
ZW> surprized that \showhyphens does not work in xelatex but in a real
ZW> text the words are hyphenated correctly.
xetex needs a redefined \showhyphens, you need to \usepackage{xltxtra}
to get the working \showhyphens in xetex.
Best,
v.