Add mention of the default file system encoding for Windows.

Misc/NEWS

@@ -2,6 +2,23 @@ What's New in Python 2.2a0?
 ===========================
 
 Core
+- Some operating systems now support the concept of a default Unicode
+  encoding for file system operations.  Notably, Windows supports 'mbcs'
+  as the default.  The Macintosh will also adopt this concept in the medium
+  term, altough the default encoding for that platform will be other than 
+  'mbcs'.
+  On operating system that support non-ascii filenames, it is common for 
+  functions that return filenames (such as os.listdir()) to return Python
+  string objects pre-encoded using the default file system encoding for
+  the platform.  As this encoding is likely to be different from Python's
+  default encoding, converting this name to a Unicode object before passing
+  it back to the Operating System would result in a Unicode error, as Python
+  would attempt to use it's default encoding (generally ASCII) rather 
+  than the default encoding for the file system.
+  In general, this change simply removes surprises when working with 
+  Unicode and the file system, making these operations work as
+  you expect, increasing the transparency of Unicode objects in this context.
+  See [????] for more details, including examples.
 
 - Float (and complex) literals in source code were evaluated to full
   precision only when running from a .py file; the same code loaded from a