<p>I'm looking for something that will let me parse Atom and RSS in Ruby and Rails. I've looked at the standard RSS library, but is there one library that will auto-detect whatever type of feed it is and parse it for me?</p>

Googleage reveals some things.  Were they not acceptable?
Simple RSS
Ruby-Feedparser
```
```
require 'simple-rss'
require 'open-uri'
rss = SimpleRSS.parse open('http://slashdot.org/index.rdf')
rss.channel.title # => "Slashdot"
```
```