Between the number keys and the silver edging at the top of the keyboard, there are 4 tabs that need to be pushed inwards in order to pop the keyboard out.
Look above the Esc, F6-F7, Prt Sc/SysRq and Numpad * areas and you should see little black tabs. Get a small flathead screwdriver (or similar device) and gently push the tabs up into the silver trimpiece. The keyboard should pop right up for you at that point. Be careful of the connector at the bottom of the keyboard. The little plastic lock is pretty small and fragile.