py-hcluster library provides Python functions for
agglomerative clustering. Its features include
* generating hierarchical clusters from distance matrices
* computing distance matrices from observation vectors
* computing statistics on clusters
* cutting linkages to generate flat clusters
* and visualizing clusters with dendrograms.

The interface is very similar to MATLAB's Statistics
Toolbox API to make code easier to port from MATLAB to
Python/Numpy. The core implementation of this library
is in C for efficiency. 

WWW:	http://code.google.com/p/scipy-cluster/