A enthusiast in China took a suggestion all the way and has implemented at least a decision tree viewer in Silverlight - I don't read Chinese, but you can see it here

Rafal Lukawiecki - consistantly one of the top TechEd Europe speakers - has been traveling around doing an extensive data mining roadshow.  Here is a review of his show in Israel, but you don't have to hear just the critics - you can also hear Rafal's point of view in this interview or even see last year's TechEd presentation.  I was there and was amazed - I had provided a lot of the material to Rafal and presented it for a "good" response, but hearing Rafal deliver it was inspirational! 

You don't have to stop there, in April, Rafal's show is going to London, and rumor tells me you'll have the chance to see him at TechEd in Orlando this year in both the developer week and the IT week speaking both on Data Mining and Security.