per suggestion on solr-user, added a mime-mapping for .xsl files to the web.xml so that the mime-type will be set correctly even if the servlet container doesn't have one configured. used application/xslt+xml instead of application/xml based on W3C XSLT recommendation since 2003/May ... tested in Firefox2 and IE6
incubator/solr/trunk/CHANGES.txt
incubator/solr/trunk/src/webapp/WEB-INF/web.xml