Have we considered how nicely this would play with scalar attributes? One could imagine appropriate Attribute::Handlers hanging their data off arbitrary scalars. Then one could imagine:

sub UNIVERSAL::property {
   require Magic::Attach;
   my $self = shift;
   my $property_name = shift;
   return Magic::Attached::attached($self, $property_name);
}

sub UNIVERSAL::but {
   require Magic::Attach;
   my $self = shift;
   my($property_name, $value) =@_;
   Magic::Attach::attach($self, $property_name, $value);
}
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and the like.

The fun begins when you start to try and implement Perl6ish tricks along the lines of return $value->but('true') or (possibly nicer) return $value :but('true'); . For this to work really well you would need have 'but' dispatch to appropriate handlers in some way (possibly through a registry system), but it's not beyond the wit of man...

Can you tell I've been thinking along these lines for a while but have lacked the appropriate tuits?