jQuery initialization

that last thing (let's call this closure an "anonymous scope") is totally valid given it is put in the right place. this construct is also considered best practice in javascript world to encapsulate your code from the global scope.

if you run it at the end of the page, you should not have any problems.
Also, the closure lacks an argument variable to hold the jquery reference you passed in (although it would work anyway :p).
You can even combine this with .noConflict() and use $ inside the closure at the same time:

(function($){
  // code
})(jQuery.noConflict())