lunatic was referring to launcher pro, I use go launcher on my Galaxy SL. These are customizeable "launchers" you get off the market. Basically, a "launcher" is the UI of your phone. Samsung phones (except for the Nexus line) come out with the TouchWiz launcher installed. These launchers dictate a lot of things about your phone's UI.
On the SGS2's default TouchWiz4 launcher, it doesnt have a "hide" feature in its app drawer but you can put all the apps you dont like into a separate folder and put it at the very end of the pages. If you install another launcher like Go Launcher or Launcher Pro which has actually more customize features, these will give you an option to hide and/or lock certain apps from appearing in the app drawer.