Abusing the language:

batsman@tux-chan:/tmp$ expand -t 2 g.rb
class A
  def self.method_added id
    puts "Adding method #{id} to #{self}"
  end
end

class A
  def a
  end
end

class A
  p self.id
  class << self
    p self.id
    def self.method_added id
      p self.id
      puts "Adding singleton method #{id} to #{self}"
    end
  end
end

class A
  def self.a
  end
end
batsman@tux-chan:/tmp$ ruby g.rb
Adding method a to A
538076252
538072582

I expected
Adding method a to A
538076252
538072582
XXXXXXXXX
Adding singleton method a to Class

Why is method_added not honored for singletons? Note it is perfectly
legal to define singletons' singleton methods:

>> class A
>>   class << self
>>     def self.foo
>>       puts "foo"
>>     end
>>   end
>> end
=> nil
>> class << A; foo; end
foo
=> nil

POLS would mean for me that singletons' singletons should behave as "normal"
singletons or be completely unavailable.

-- 
 _           _                             
| |__   __ _| |_ ___ _ __ ___   __ _ _ __  
| '_ \ / _` | __/ __| '_ ` _ \ / _` | '_ \ 
| |_) | (_| | |_\__ \ | | | | | (_| | | | |
|_.__/ \__,_|\__|___/_| |_| |_|\__,_|_| |_|
	Running Debian GNU/Linux Sid (unstable)
batsman dot geo at yahoo dot com

<sct> Anyone want the new supermount? :)
<klogd> whats new aboutit
<sct> klogd: It cleans whiter than white. :)
	-- Seen on #Linux