Hi! Please, add this feature. My diff in axes.py looks quite simple:

--- /home/sh/Downloads/matplotlib-1.3.1/lib/matplotlib/axes.py 2013-10-10 16:42:48.000000000 +0400
+++ matplotlib/axes.py  2013-10-23 16:52:11.793788510 +0400
@@ -5307,7 +5307,7 @@
 
     def pie(self, x, explode=None, labels=None, colors=None,
             autopct=None, pctdistance=0.6, shadow=False,
-            labeldistance=1.1, startangle=None, radius=None):
+            labeldistance=1.1, startangle=None, radius=None, counterclock=True):
         r"""
         Plot a pie chart.
 
@@ -5420,12 +5420,12 @@
         i = 0
         for frac, label, expl in cbook.safezip(x, labels, explode):
             x, y = center
-            theta2 = theta1 + frac
+            theta2 = theta1 + frac if counterclock else theta1 - frac
             thetam = 2 * math.pi * 0.5 * (theta1 + theta2)
             x += expl * math.cos(thetam)
             y += expl * math.sin(thetam)
 
-            w = mpatches.Wedge((x, y), radius, 360. * theta1, 360. * theta2,
+            w = mpatches.Wedge((x, y), radius, 360. * min(theta1, theta2), 360. * max(theta1, theta2),
                       facecolor=colors[i % len(colors)])
             slices.append(w)
             self.add_patch(w)