FSEvents is the directory change notification API in Leopard, 10.5. As polling is no longer a supported notification method, it would be excellent if samba could use the emerging notification capabilities in various operating systems.
'This API provides a mechanism to notify clients about directories they ought to re-scan in order to keep their internal data structures up-to-date with respect to the true state of the file system. (For example, when files or directories are created, modified, or removed.) It sends these notifications "in bulk", possibly notifying the client of changes to several directories in a single callback. By using the API, clients can notice such changes quickly, without needing to resort to recursive polling/scanning of the file system.'
I haven't investigated FSEvents enough to know whether it would be suitable for file change notifications.
Not sure when I would get time to look at this. I'm happy to review patches though.