require 'xrd'
xrd = XRD.fetch_and_parse(
  'http://www.google.com/s2/webfinger/?q=acct%3Agooglebuzz%40gmail.com'
)
xrd.subject
# => #<Addressable::URI:0x80fb3864 URI:acct:[email protected]>
xrd.aliases
# => [#<Addressable::URI:0x80fb3224 URI:http://www.google.com/profiles/googlebuzz>]
xrd.links(:media_type => 'application/atom+xml')
# => [#<XRD::Link:0x80fbc11c HREF:https://www.googleapis.com/buzz/v1/activities/111062888259659218284/@public>]
xrd.links(:rel => 'describedby')
# => [
#   #<XRD::Link:0x80fbd224 HREF:http://www.google.com/profiles/googlebuzz>,
#   #<XRD::Link:0x80fbc914 HREF:http://www.google.com/s2/webfinger/?q=acct%3Agooglebuzz%40gmail.com&fmt=foaf>
# ]
xrd.links(:rel => 'describedby', :media_type => 'text/html')
# => [#<XRD::Link:0x80fbd224 HREF:http://www.google.com/profiles/googlebuzz>]