Data Mining

I've been trying to figure out how data mining is used in the trading space - it doesn't appear that the traditional vendors of ETL tools, such as Ab Initio, Data-Stage/Ascential, Informatica, etc.. are very dominant in this space.  Instead I am seeing companies such as GreenPlum and Vertica.  GreenPlum appears to be used by NASDAQ and NYSE (of course one of the board members of GreenPlum is also one of the founders of Archipelago...)  Netezza is another player that I heard mentioned while still in my traditional ETL days.
Here is an interesting article from GigaOm talking about the data mining renaissance.