rake notesが出してくれる範囲。

configの下も出したかったので調べた。

rails-2.3.5/lib/source_annotation_extractor.rb

 48   # Returns a hash that maps filenames under +dirs+ (recursively) to arrays
 49   # with their annotations. Only files with annotations are included, and only
 50   # those with extension +.builder+, +.rb+, +.rxml+, +.rjs+, +.rhtml+, and +.erb+
 51   # are taken into account.
 52   def find(dirs=%w(app lib test))
 53     dirs.inject({}) { |h, dir| h.update(find_in(dir)) }
 54   end

ここね。