HI,
I am using a DPM build (VCM 8.0 / VAP 8.1) on Tomcat.  I've  created an RSS feed with a grid and content-publisher  portlet.  
But the portal always responds with "text/html" instead of  "application/rss+xml" in the HTTP  header.  Below is part of an example response header:
HTTP/1.1 200 OK 
 Server: Apache-Coyote/1.1 
 Set-Cookie:  JSESSIONID=9783227D8AB1BFB04C0A0507E7BDD92E; Path=/sitename 
  Set-Cookie: VignettePortal-NavTreeState-sitename="";  Expires=Thu, 01-Jan-1970 00:00:10 GMT; Path=/ 
 Cache-Control:  no-cache 
Content-Type: text/html;charset=UTF-8   
 Transfer-Encoding: chunked 
 Date: Mon, 11 Jul 2011  14:24:30 GMT
  
I tried putting these JSP lines in both grid and portlet, but portal  still insists on "text/html":
<%@ page contentType="application/rss+xml"  pageEncoding="UTF-8" %>
<%  response.setContentType("application/rss+xml;charset=UTF-8");  %>
  
Also tried adding the MIME type to the portal web.xml file as  below and create an "rss" presentation format just to get  the ".rss" extension in the URL, but it didn't help  either.  
<mime-mapping>
               <extension>rss</extension>
               <mime-type>application/rss+xml</mime-type>
  </mime-mapping>
  
Anybody know of a way to force the portal to respond with a MIME type  other than "text/html" on a DPM template?