Noodlesoft released Hazel 3.0.14 to enable you to edit notification options from the file cleanup utility when running in OS X 10.8 Mountain Lion. Accessed via the gear pull-down, you can select Notification Center or Growl (if you have the latter installed) and specify which kinds of notifications should be displayed. (By default, Notification Center gets the nod if both are available.) The update also fixes instances of Hazel not keeping track of Trash if it is empty on startup and more reliably matches patterns with accented characters. Noodlesoft subsequently issued version 3.0.15 to fix a crash in notification options and a disabling of the gear pull-down when notification options are available but no folders are present. ($25 new, free update, 6.2 MB, release notes)
Mac OS X Services in Snow Leopard
Mac OS X Services let one application supply its powers to another; for example, a Grab service helps TextEdit paste a screenshot into a document. Most users either don't know that Services exist, because they're in an obscure hierarchical menu (ApplicationName > Services), or they mostly don't use them because there are so many of them.
Snow Leopard makes it easier for the uninitiated to utilize this feature; only services appropriate to the current context appear. And in addition to the hierarchical menu, services are discoverable as custom contextual menu items - Control-click in a TextEdit document to access the Grab service, for instance.
In addition, the revamped Keyboard preference pane lets you manage services for the first time ever. You can enable and disable them, and even change their keyboard shortcuts.