The <code>\usemodule[bibltx]</code> line is needed because <tt>xampl.bib</tt> uses LaTeX commands and defines them using LaTeX syntax. The <tt>bibltx</tt> module allows ConTeXt to understand some such constructions (which is enough for it to work with <tt>xampl.bib</tt>).
Note: Since Bibtex is added to the context core, no external module is necessary. It is sufficient to type for example (minimal):
<texcode>
\setupbibtex[database=bib]
\starttext
\completepublications
\stoptext
<\texcode>
== Changing the way you show the publication list ==
[[Category:Modules]]
==What can I do, if no entries are shown?==
Check if a <code>\jobname.bbl</code> - file is generated. If it is empty, try manually running
bibtex <filename>
In case of an error message like <code>I couldn't open style file cont-no.bst</code>, you can try
mktexlsr
in root terminal. Bibtex uses LS-R to find these files.