> 
> Is there any painless workaround to this?
> 

Either use Marshal.dump instead, or set parser to nil on the feed object 
before YAMLification:

   feed = FeedNormalizer.parse(open("http://waxy.org/links/index.xml"))
   feed.parser = nil  # [1]
   YAML.dump(feed)    # now it should work...

   # [1] or maybe feed.parser = feed.parser.to_s if you don't
   # want to lose meta info.


I intend to fix this in the next release so that pre-serialization 
object tampering isn't required :)

Hope that helps.

Andy