diff -r 6c5245427ccb Lib/distutils/command/sdist.py
--- a/Lib/distutils/command/sdist.py	Fri Apr 15 17:55:36 2011 -0700
+++ b/Lib/distutils/command/sdist.py	Sun Jun 12 09:41:47 2011 +0800
@@ -363,6 +363,11 @@
 
         content = self.filelist.files[:]
         content.insert(0, '# file GENERATED by distutils, do NOT edit')
+        
+        # We always use '/' as file path separator in MANIFEST file
+        # To fix bug: http://bugs.python.org/issue828450
+        content = [line.replace('\\','/') for line in content]
+        
         self.execute(file_util.write_file, (self.manifest, content),
                      "writing manifest file '%s'" % self.manifest)
 
diff -r 6c5245427ccb Lib/distutils/tests/test_sdist.py
--- a/Lib/distutils/tests/test_sdist.py	Fri Apr 15 17:55:36 2011 -0700
+++ b/Lib/distutils/tests/test_sdist.py	Sun Jun 12 09:41:47 2011 +0800
@@ -47,13 +47,13 @@
 README
 inroot.txt
 setup.py
-data%(sep)sdata.dt
-scripts%(sep)sscript.py
-some%(sep)sfile.txt
-some%(sep)sother_file.txt
-somecode%(sep)s__init__.py
-somecode%(sep)sdoc.dat
-somecode%(sep)sdoc.txt
+data/data.dt
+scripts/script.py
+some/file.txt
+some/other_file.txt
+somecode/__init__.py
+somecode/doc.dat
+somecode/doc.txt
 """
 
 class SDistTestCase(PyPIRCCommandTestCase):
@@ -233,7 +233,7 @@
         f = open(join(self.tmp_dir, 'MANIFEST'))
         try:
             manifest = f.read()
-            self.assertEqual(manifest, MANIFEST % {'sep': os.sep})
+            self.assertEqual(manifest, MANIFEST)
         finally:
             f.close()
 
@@ -419,6 +419,65 @@
             f.close()
 
         self.assertEqual(manifest, ['README.manual'])
+        
+    def test_manifest_sep(self):
+        # http://bugs.python.org/issue828450
+        # check if every file path line in MANIFEST takes '/' as path 
+        # separator, thus Unix can read MANIFEST file generated by Windows 
+        # without any problem, and the reverse is ok
+        
+        dist, cmd =  self.get_cmd()
+        cmd.ensure_finalized()
+        cmd.run()
+        
+        # always use slash character ('/') as separator
+        MANIFEST_STR = """\
+        # file GENERATED by distutils, do NOT edit
+        README
+        setup.py
+        somecode/__init__.py
+        """
+        
+        f = open(cmd.manifest)
+        try:
+            manifest = [line.strip() for line in f.read().split('\n')
+                        if line.strip() != '']
+            
+            manifest_slash = [line.strip() for line in MANIFEST_STR.split('\n')
+                                if line.strip() != '']
+            self.assertEqual(manifest, manifest_slash)
+        finally:
+            f.close()
+    
+    def test_read_manifest(self):
+        # check if it's ok to read the MANIFEST file when all the file paths
+        # in it has taken '/' as separator, especially when Python use '\' as
+        # the separator on a specific system
+        
+        dist, cmd =  self.get_cmd()
+        cmd.ensure_finalized()
+        # cmd will run later, thus know what different thing happens
+        
+        MANIFEST_STR = """\
+        README
+        setup.py
+        somecode/__init__.py
+        """        
+        
+        f = open(join(self.tmp_dir, 'MANIFEST'), 'w')
+        try:
+            # using a more easy way to test: directly write the string into 
+            # the MANIFEST file instead creating files
+            f.write(MANIFEST_STR)
+            filelist = [line.strip() for line in MANIFEST_STR.split('\n')
+                        if line.strip() !='']
+            os.sep = '\\'
+            cmd.run()# cmd run now
+            filelist_generated = [line.strip().replace('\\','/') for line in \
+                                    cmd.filelist.files[:] if line.strip() !='']
+            self.assertEqual(filelist, filelist_generated)
+        finally:
+            f.close()
 
 def test_suite():
     return unittest.makeSuite(SDistTestCase)