You don't say which version of Ubuntu you're using. It has been removed in the development version of Unity, and it won't be used in 12.04. Or rather; it has been altered to work like the other lenses, only with different types of categories. The big buttons are gone.
It is possible that you can install it in your version of Ubuntu, from a PPA, but I would rather recommend that you wait until you're comfortable with it and upgrade to 12.04.
You don't say which version of Ubuntu you're using. It has been removed in the development version of Unity, and it won't be used in 12.04. Or rather; it has been altered to work like the other lenses, only with different types of categories. The big buttons are gone.
It is possible that you can install it in your version of Ubuntu, from a PPA, but I would rather recommend that you wait until you're comfortable with it and upgrade to 12.04.