"Favorite" public folders are recorded in NON_IPM_SUBTREE/Shortcuts.
One file for each favorite.

Important properties:

PR_FAV_DISPLAY_NAME      - PR_DISPLAY_NAME of referent
PR_FAV_DISPLAY_ALIAS     - user-chosen display name, or unset
PR_FAV_PUBLIC_SOURCE_KEY - PR_SOURCE_KEY of referent
PR_FAV_AUTOSUBFOLDERS    - 1 if auto add all/immed subfolders, or unset
PR_FAV_PARENT_SOURCE_KEY - PR_FAV_PUBLIC_SOURCE_KEY of parent
PR_FAV_LEVEL_MASK        - depth in hierarchy (first level is 1)
PR_FAV_INHERIT_AUTO      - 1 if auto add all subfolders, or unset
PR_FAV_DEL_SUBS          - set if AUTOSUBFOLDERS is set. Array of:
                             PR_SOURCE_KEY,  00 00,  02 00 00 00

The PR_FAV_PUBLIC_SOURCE_KEY can be used to find the public folder
that this favorite points to. Eg:

  http://schemas.microsoft.com/mapi/proptag/x7c020102 (PR_FAV_PUBLIC_SOURCE_KEY):
    50 2d 6a fd 16 1e f2 43 89 95 e1 d9 29 cf 92 eb    P-j....C....)...
    00 00 00 00 00 32                                  .....2

implies: http://shrewdness.xcs.ximian.com/public/-FlatUrlSpace-/502d6afd161ef2438995e1d929cf92eb-32
(and you can query for the DAV:href property on that to find the
"normal" URL for the folder)
