<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:key name="k" match="set2/*" use="@id"/>
<xsl:output indent="yes"/>
  <xsl:template match="doc">
    <set2>
      <xsl:copy-of select="for $e in set1/* return key('k',$e/@id)"/>
    </set2>
  </xsl:template>
</xsl:stylesheet>

David, that's a cool solution.  Unfortunately I glossed over the fact
that there is some manipulation of the data within the second set
going on.  I'm going to experiment with trying this approach within a
for-each and/or apply-template. as well as attempting to invert the
problem as suggested by Eric.

--
Peter Hunsberger