RSS and Atom feed fetching


Which feed fetching library should I use? I need support for
<feedburner:origLink>, <enclosure>, multiple <comment> elements, all
RSS dialects and so on...

The parser should return a data structure that is independent of the
feed format, i.e. the same for RSS1, RSS2 and Atom, ...

Any plugins or libraries that you could recommend? Is there something
like UFP for Ruby?