sys.platform on Mac OS X is now "darwin", without any version number appended.
This should probably go into NEWS (who's responsible for that?).
diff --git a/configure.in b/configure.in
index 09aa5de..e9c90ad 100644
--- a/configure.in
+++ b/configure.in
@@ -68,6 +68,7 @@
 
 	case $MACHDEP in
 	cygwin*) MACHDEP="cygwin";;
+	darwin*) MACHDEP="darwin";;
 	'')	MACHDEP="unknown";;
 	esac
 fi