I was verifying some less traveled parts of the next version of my site and noticed that the media type/mime for my RSS feed was application/xhtml+xml in Firefox though application/rss+xml in Opera. I'm pretty sure it's supposed to be application/rss+xml though I figure this is some sort of Gecko bug? My RSS feed is perfectly valid without warnings and unless I open an RSS feed as a local file it's always served as application/xhtml+xml; locally Firefox serves it as text/xml. Thoughts please?
I set PHP to serve the RSS feed as application/rss+xml and it validates as an Atom 2.0 feed. I also tried some other media types/mimes such as application/rdf+xml and text/xml (even though it's not supposed to be served as that). I ensured that Apache wasn't overriding the media type via .htaccess at any directory level from root up to and including where the RSS feed is located. I verified this both locally on my WAMP server and on my test environment on my live LAMP server.
It sounds like you've got it set up right, then. However, I did notice that application/rss+xml is not an IANA-registered MIME type, so it may not be entirely standardized yet. I saw a forum post listed in Google where a guy reports having to use text/rss+xml or some-such to work with IE, Firefox, and early versions of Safari.
I am using application/rss+xml and it's an RSS 2.0 feed. When I changed the media type it still didn't take in Firefox however it did in Opera. Both media types work in Safari 2 and IE7 without any hitches (resetting Safari and clearing everything in IE7 naturally between switching media types).
So is application/atom+xml the way to go? Wiki's RSS page reports that the media type is the one I have been originally using...wonderfully confusing! ;)