Thanks @egreg! – Your example with the verbments package works very well. But I was looking for a solution for the listings package, so I can't accept this as an answer … :-/ Also I'm missing many options with the verbments package that I'm using wit the listings package. But I really like the lexer method used by pygmentize! Thanks for your hints about compatibility and not recommended packages, too. :)

I just want to include some sourcecode by using the listings package wit XeTeX.

Here is my minimal example:

% !TEX TS-program = XeLaTeX
% !TEX encoding = UTF-8 Unicode
\documentclass[xetex]{scrreprt}
\usepackage{xltxtra}
\defaultfontfeatures{Mapping=tex-text}
\setmonofont[Scale=.8]{Inconsolata}
\usepackage{bold-extra}
\usepackage{upquote}
\usepackage{listings}
\lstset{
    basicstyle=\ttfamily\scriptsize,
    keywordstyle=\bfseries,
    numbers=left,
    inputencoding=utf8x,
    extendedchars=true,
    showlines=true,
    upquote=true,
    showstringspaces=false
}
\lstdefinelanguage{turtle} {
  morekeywords={@prefix,@base,@forSome,@forAll,@keywords},
%   literate=%
%       *{``}{``}{1}
%       {''}{''}{1}
%       {„}{``}{1}
%       {“}{''}{1},
}

\begin{document}
\begin{lstlisting}[language=turtle]
@prefix crm:  <http://www.cidoc-crm.org/cidoc-crm/> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

<http://my.domain/object/1>
  rdf:type
    crm:E22_Man-Made_Object ;
  rdfs:label 
    "„David“ Skulptür …", "This is another ‚test‘ …" ;
  crm:P102_has_title 
    <http://my.domain/title/1> ;
  crm:P108i_was_produced_by
    <http://my.domain/production/1> ;
  crm:P31i_was_modified_by
    <http://my.domain/modification/1> .
\end{lstlisting}
\end{document}

This produces te following output: example listing with wrong quotation marks

As you can see in line 8 (the last sign at the end) and line 9 (after the first quotation mark; in front of the word test) the quotation marks are wrong/incorrect. – David should be surrounded by (German) double quotation marks („David“) and test with (German) single quotation marks (‚test‘).

→ Does someone know how to fix that/produce that?

Another problem in line 9 is the display of typographical quotation marks (opening and closing) for the whole string ("„David“ Skulptür …"). I can only fix this by commenting out \defaultfontfeatures{Mapping=tex-text} in the preamble.

→ Again: Does someone know how to fix that (without disabling \defaultfontfeatures)?

Thanks a lot and best regards!

PS: The disabled literate option in the MWE doesn't change anything if is enabled …