New in Wolfram Mathematica 6: High-Level String Computation  previous | next 
Statistical Semantic Analysis
With its WordData capabilities, Mathematica 6 makes immediate forms of semantic analysis possible. Here is the moving average of the number of word senses in the U.S. Declaration of Independence, with the signature block at the end visibly distinct.
In[1]:=

Click for copyable input
ListLinePlot[

 MovingAverage[

  Length[WordData[ToLowerCase[#]]] & /@ 

   Flatten[StringCases[

     ExampleData[{"Text", "DeclarationOfIndependence"}, "Words"], 

     LetterCharacter ..]], 20], Filling -> Axis, 

 PlotRange -> {0, All}, Frame -> True]
Out[1]=