WordNet (r) 3.0 (2006):

poetic justice
    n 1: an outcome in which virtue triumphs over vice (often
         ironically) [syn: poetic justice, just deserts]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "poetic justice":
   ars poetica, defensibility, drumhead justice, dueness,
   equitableness, equity, evenhandedness, give-and-take, justice,
   justifiability, justifiableness, justification, justness,
   lawfulness, legality, measure for measure, meetness, nemesis,
   poetcraft, poetic language, poetic license, poeticism, poetics,
   properness, propriety, retributive justice, right, rightfulness,
   rightness, rude justice, scales of justice, summary justice,
   versecraft, versemaking, versification, warrantability,
   warrantedness, what is right