Vladimir Marangozov's long-awaited malloc restructuring.
For more comments, read the patches@python.org archives.
For documentation read the comments in mymalloc.h and objimpl.h.

(This is not exactly what Vladimir posted to the patches list; I've
made a few changes, and Vladimir sent me a fix in private email for a
problem that only occurs in debug mode.  I'm also holding back on his
change to main.c, which seems unnecessary to me.)
diff --git a/Modules/pcremodule.c b/Modules/pcremodule.c
index 4d2aa72..6b9f960 100644
--- a/Modules/pcremodule.c
+++ b/Modules/pcremodule.c
@@ -79,7 +79,7 @@
 	PyObject *arg;
 {
 	PcreObject *self;
-	self = PyObject_NEW(PcreObject, &Pcre_Type);
+	self = PyObject_New(PcreObject, &Pcre_Type);
 	if (self == NULL)
 		return NULL;
 	self->regex = NULL;
@@ -95,7 +95,7 @@
 {
 	if (self->regex) (pcre_free)(self->regex);
 	if (self->regex_extra) (pcre_free)(self->regex_extra);
-	PyMem_DEL(self);
+	PyObject_Del(self);
 }