diff -r a3aba2148186 Lib/imp.py
--- a/Lib/imp.py	Tue Jun 26 14:08:15 2012 -0400
+++ b/Lib/imp.py	Tue Jun 26 16:17:25 2012 -0400
@@ -11,7 +11,7 @@
                   init_builtin, init_frozen, is_builtin, is_frozen,
                   _fix_co_filename, extension_suffixes)
 # Could move out of _imp, but not worth the code
-from _imp import get_magic, get_tag
+from _imp import get_magic
 
 from importlib._bootstrap import new_module
 from importlib._bootstrap import cache_from_source
@@ -37,6 +37,11 @@
 IMP_HOOK = 9
 
 
+def get_tag():
+    """Return the magic tag string for the current version of Python's 
+    magic number, as defined by the current implementation"""
+    return sys.implementation.cache_tag
+
 def get_suffixes():
     warnings.warn('imp.get_suffixes() is deprecated; use the constants '
                   'defined on importlib.machinery instead',
diff -r a3aba2148186 Lib/importlib/_bootstrap.py
--- a/Lib/importlib/_bootstrap.py	Tue Jun 26 14:08:15 2012 -0400
+++ b/Lib/importlib/_bootstrap.py	Tue Jun 26 16:17:25 2012 -0400
@@ -1452,7 +1452,7 @@
     # Constants
     setattr(self_module, '_relax_case', _make_relax_case())
     setattr(self_module, '_MAGIC_NUMBER', _imp_module.get_magic())
-    setattr(self_module, '_TAG', _imp.get_tag())
+    setattr(self_module, '_TAG', sys.implementation.cache_tag)
     if builtin_os == 'nt':
         SOURCE_SUFFIXES.append('.pyw')