I’m currently attending Pascal Costanza’s CLOS, MOP and ContextL tutorial at ILC ’09. Here is the relevant URL for the tutorial files (Common Lisp code and PDF slides):
About 45 people attended in the morning session. One of the nicest part of the morning tutorial was implementing the Python object model in 50-60 lines of CLOS and MOP and being able to use Python style classes and adding object properties on the fly.
The afternoon session concentrated on ContextL and explained the concept of having layers to have contexts in Lisp programs with concrete examples.