The Offline mode 'Work Offline' should become available. There is another bug, 156552, similar to this, however it has been long enough to state that the menu item hasen't been there recently enough for it's summary to hold relevance. It appears that MainMenu.nib still holds support for Offline mode, and a simple menu item devoted to it would suffice. I recomend a menu item under About Navigator in the Application menu labeled Work Offline.
*** Bug 176651 has been marked as a duplicate of this bug. ***
Is there any good way to handle this at the Location Manager level?
I've updated the summary of bug 156552 so it's more general and not out of date. *** This bug has been marked as a duplicate of 156552 ***