Add links to understand the GIL

docs/scenarios/speed.rst

@@ -11,7 +11,13 @@ Context
 The GIL
 -------
 
+`The GIL`_ (Global Interpreter Lock) is how Python allows multiple threads to operate at the same time. Python's
+memory management isn't entirely thread-safe, so the GIL is requried to prevents multiple threads from running
+the same Python code at once.
 
+David Beazley has a great `guide`_ on how the GIL operates. He also covers the `new GIL`_ in Python 3.2. His
+results show that maximizing performance in a Python application requires a strong understanding of the GIL,
+how it affects your specific application, how many cores you have, and where your application bottlenecks are.
 
 C Extentions
 ------------
@@ -20,8 +26,8 @@ C Extentions
 The GIL
 -------
 
-
+`Special care`_ must be taken when writing C extensions to make sure you register your threads
-
+with the interpreter.
 
 C Extentions
 ::::::::::::
@@ -56,4 +62,8 @@ Multiprocessing
 ---------------
 
 
-.. _`PyPy`: http://pypy.org
+.. _`PyPy`: http://pypy.org
+.. _`The GIL`: http://wiki.python.org/moin/GlobalInterpreterLock
+.. _`Understanding GIL`: http://www.dabeaz.com/python/UnderstandingGIL.pdf
+.. _`New GIL`: http://www.dabeaz.com/python/NewGIL.pdf
+.. _`Thread State`: http://docs.python.org/c-api/init.html#threads