I've used PMD's Copy-and-Paste-Detector and integrated it into CruiseControl by using the following wrapper script (be sure to have the pmd jar in the classpath).
Our check runs nightly. If you wish to limit output to list only files from the current change set you might need some custom programming (idea: check all and list only duplicates where one of the changed files is involved. You have to check all files because a change could use some code from a non-changed file). Should be doable by using XML output and parsing the result. Don't forget to post that script when it's done ;)
For starters the "Text" output should be ok, but you will want to display the results in a user-friendly way, for which i use a perl script to generate HTML files from the "xml" output of CPD. Those are accessible by posting them to the tomcat where cruise's reporting jsp resides. The developers can view them from there and see the results of their dirty hacking :)
It runs quite fast, less than 2 seconds on 150 KLoc code (empty lines and comments not counted in that number).
duplicatecheck.xml:
<project name="duplicatecheck" default="cpd">
<property name="files.dir" value="dir containing your sources"/>
<property name="output.dir" value="dir containing results for publishing"/>
<target name="cpd">
<taskdef name="cpd" classname="net.sourceforge.pmd.cpd.CPDTask"/>
<cpd minimumTokenCount="100"
language="cpp"
outputFile="${output.dir}/duplicates.txt"
ignoreLiterals="false"
ignoreIdentifiers="false"
format="text">
<fileset dir="${files.dir}/">
<include name="**/*.h"/>
<include name="**/*.cpp"/>
<!-- exclude third-party stuff -->
<exclude name="boost/"/>
<exclude name="cppunit/"/>
</fileset>
</cpd>
</target>
