Try running the following program:

================
require 'open-uri'

feed_url = "http://www.slate.com/rss"

result1 = open(feed_url).read
puts "Saving result1.xml:"
File.open("result1.xml", "w") {|f| f.write(result1)}

result2 = `curl -L #{feed_url}`
puts "Saving result2.xml:"
File.open("result2.xml", "w") {|f| f.write(result2)}

command = "diff result1.xml result2.xml"
puts system(command)
================

result1 should be identical to result2, but it turns out that the feed
that open-uri fetches is outdated content (by over a month), while the
feed that curl fetches is up-to-date. Can anyone please explain what
is going on?

Thanks!