Gross, but hopefully temporary solution for namespaced classes and old versions of libxml

app/models/activity_streams/photo.rb

@@ -5,7 +5,7 @@
 class ActivityStreams::Photo < Post
   include Diaspora::Socketable
 
-  xml_name "activity_streams::_photo"
+  xml_name self.name.underscore.gsub!('/', '-')
   xml_attr :image_url
   xml_attr :image_height
   xml_attr :image_width

lib/diaspora/parser.rb

@@ -7,7 +7,8 @@ module Diaspora
     def self.from_xml(xml)
       doc = Nokogiri::XML(xml) { |cfg| cfg.noblanks }
       return unless body = doc.xpath("/XML/post").children.first
-      body.name.camelize.constantize.from_xml body.to_s
+      class_name = body.name.gsub('-', '/')
+      class_name.camelize.constantize.from_xml body.to_s
     end
   end
 end