[jQuery] Frustrating Scope Question with getJSON

[dysfunct]

There's some sort of scope issue here that I cant seem to get passed.
I'd ideally just like the function to return the shortUrl from the
json results but can't seem to get it anywhere but the callback
function.

function shortenURL(url){
         var apiKey = 'APIKEY';
         var apiLogin = 'LOGIN';
         var shortURL;
         $.getJSON("http://api.bit.ly/shorten?version=2.0.1&longUrl=";
+ url + "&login=" + apiLogin + "&apiKey=" + apiKey, function(data){
                                shortURL = data.results[url].shortUrl;
                    });
         return shortURL;
                }