>This patch seems to be working. But I'm not familier with yaml, so can anyone
>test this? (I found another problem on Numeric. Rational and Complex are not
>treated properly)

Sorry, patch was broken. Try again...

Index: lib/yaml/rubytypes.rb
===================================================================
RCS file: /src/ruby/lib/yaml/rubytypes.rb,v
retrieving revision 1.16.2.9
diff -u -p -r1.16.2.9 rubytypes.rb
--- lib/yaml/rubytypes.rb	20 Sep 2005 06:46:45 -0000	1.16.2.9
+++ lib/yaml/rubytypes.rb	3 Jan 2006 08:00:21 -0000
@@ -352,7 +352,17 @@ class Date
 	end
 end
 
-class Numeric
+class Integer
+    yaml_as "tag:yaml.org,2002:int"
+       def to_yaml( opts = {} )
+               YAML::quick_emit( nil, opts ) do |out|
+            out.scalar( "tag:yaml.org,2002:int", self.to_s, :plain )
+        end
+       end
+end
+
+class Float
+    yaml_as "tag:yaml.org,2002:float"
 	def to_yaml( opts = {} )
 		YAML::quick_emit( nil, opts ) do |out|
             str = self.to_s
@@ -363,19 +373,11 @@ class Numeric
             elsif str == "NaN"
                 str = ".NaN"
             end
-            out.scalar( taguri, str, :plain )
+            out.scalar( "tag:yaml.org,2002:float", str, :plain )
         end
 	end
 end
 
-class Fixnum
-    yaml_as "tag:yaml.org,2002:int"
-end
-
-class Float
-    yaml_as "tag:yaml.org,2002:float"
-end
-
 class TrueClass
     yaml_as "tag:yaml.org,2002:bool#yes"
 	def to_yaml( opts = {} )