In the monobook skin and others with "p-cactions" links (edit, history, watch, etc. on the top of pages in monobook) a new "patrol links" link/tab will be added to activate the patrol links. On skins without this (Classic) the links will be turned on by default. You can also turn them on by default in other skins using an option described below.
In skins where the links are not always on by default, the links can also be turned off using the "hide patrol links" button (and then restored using the "patrol links" button again).