Using variants of Wu and Palmer (1994) on the 374 SAT analogies of Turney (2005), Veale (2004) reports a success rate of 38-44% using only WordNet-based similarity.
turney (2005) reports up to 55% success on the same analogies, partly because his approach aims to match implicit relations rather than explicit concepts, and in part because it uses a divergent process to gather from the web as rich a perspective as it can on these latent relationships.