title: rpart node assignment
body: <p>Is it possible to extract the node assignment for a fitted <code>rpart</code> tree? What about when I apply the model to new data?  </p>
  
  <p>The idea is that I would like to use the nodes as a way to cluster my data.  In other packages (e.g. SPSS), I can save the predicted class, probabilities, and node number for further analysis. </p>
  
  <p>Given how powerful R can be, I imagine there is a simple solution to this.</p>