When using the new Safari RSS last night, I was surpised to see that it detected the embedded FOAF data within the feed (My LJ Feed).
Safari RSS seems to support RSS and FOAF intergration: It requests <channel /> URL from RSS and parses FOAF found with Auto-Discovery.
The new version of Mac OS X, Tiger, was released today and it has an RSS screensaver.
Tiger also has a native support for RSS screensaver. So cool.