To everyone talking about "sentiment analysis": that's not easy. Sentences like "John has stupidly said foo[1], and even went so far as to say bar[2] (which was demolished by Jane[3] and Jan[4]); he's now capitulated[5]" would be quite difficult to parse. The following articles may also be instructive: all by the same author, all quite critical, but with links with quite different intentions.
http://scienceblogs.com/goodmath/2009/05/dembski_responds.ph... http://scienceblogs.com/goodmath/2009/12/id_garbage_csi_as_n... http://scienceblogs.com/goodmath/2009/08/quick_critique_demb...