Did you ever call the URL of a RSS feed directly? If not you should definitly try the feed for news.typo3.org!

To me it seems that Rupert, who is responsible for the news site, has some time left to play with things like XSLT. The cool thing is that for feed aggegators the feed works like always, but at the moment you visit it with your browser an XSLT stylesheet gets applied and the feed is nicely formated as you can see.

There're actually two ways for styling feeds, here's a tutorial on how to style feeds with CSS and XSLT.

[Update]
Now you might ask how to achieve this with your own feeds generated by tt_news. Let's have a look at it:

The good thing is that tt_news generates the feeds from a template which is a requirement not only for doing this but also for easy adding of new feed formats. If you take a look into the /typo3conf/ext/tt_news/res folder you will find the templates for RSS (rss_0_91.tmpl and rss_2.tmpl), RDF (rdf.tmpl) and ATOM (atom_0_3.tmpl and atom_1_0.tmpl) feeds.

Now we need to modify these templates to add the XSLT sylesheet. But hold on! If we're going to edit the templates right in place we will loose those changes with the next update of tt_news. To circumvent this issue we can simply copy the RSS template to a folder in /fileadmin. This copy can be edited savely and changes will stay intact with the next update. To let tt_news know of our modified RSS template we need to add a line of TYPOscript to our configuration:

plugin.tt_news.displayXML.rss2_tmplFile = fileadmin/new_template_folder/rss_2.tmpl

Now open that copy of the template and after the first line insert the reference to your XSLT stylesheet:

<?xml-stylesheet type="text/xsl" href="http://www.example.com/fileadmin/path/to/your/xslt/stylesheet/rss.xsl" media="screen"?>

Save the template and you're done.