(somehow my first reply was eaten by that rabbit, so I'll repeat myself)
the graphviz/dot program supports utf-8 encoded files natively in 'dot' and 'plain' format,
the dotviewer might be used to view non-sourcecode dot files, ie, standalone,
the dotviewer can and has been used to visualize nodes in a parsetree or AST, where unicode characters might appear
(Consider a simple grammar for an arithmetic expression evaluator that allows unicode variables, eg, lamdba
in its expression),
probably, my proposal can help ease the transition to py3k.
(tests have been added)
Please note that I do not at all consider this pull request important leave alone critical.