Judging the quality of clustering

[Pat Ferrel]

So many questions about best k, how to choose t1 and t2, how much help 
is dimensional reduction would have clear answers if we had a way to 
judge the quality of clusters.

Various methods were discussed here for a time: 
http://www.lucidimagination.com/search/document/dab8c1f3c3addcfe/validating_clustering_output

Has there been any work on building a measure of quality?