Question on this one:

<snip>
@@ -126,7 +131,7 @@ def load_compiled(name, pathname, file=N
 # XXX deprecate
 def load_package(name, path):
     if os.path.isdir(path):
-        extensions = _bootstrap._SOURCE_SUFFIXES + [_bootstrap._BYTECODE_SUFFIX]
+        extensions = machinery.SOURCE_SUFFIXES[:] + [machinery.BYTECODE_SUFFIXES]
         for extension in extensions:
             path = os.path.join(path, '__init__'+extension)
             if os.path.exists(path):
</snip>

Should that be the following?

  extensions = machinery.SOURCE_SUFFIXES[:] + machinery.BYTECODE_SUFFIXES[:]

Also, why the "[:]"?

Finally, in a couple spots you use the first element of the list (like the old case of "machinery.SOURCE_SUFFIXES[0]" in source_from_cache() and the new one in find_module()).  Will this be a problem where the source file has one of the other suffixes?  I'm not sure it's a big enough deal for the moment to worry about, but thought I'd ask.  :)