Google URL Shortner error

Hi I'm trying to make use of the Google URL Shortener API and running in to an issue.

In a suitelet I have this code :
var gurl = "https://www.googleapis.com/urlshortener/v1/url?key=this-is-not-my-api-key-ahem";

var data = {};
data.longUrl = "http://www.thisisnottherealverylongurliamusing.com";
var params = new Array();
params['data'] =data;
params['method'] = 'POST';
var headers = new Array();
headers['Content-Type'] = 'application/json';

var shorturl = nlapiRequestURL(gurl, params, headers, null);
var resulturl = shorturl.getBody();

the response I get back is :
{  "error": {   "errors": [    {     "domain": "global",     "reason": "parseError",     "message": "Parse Error"    }   ],   "code": 400,   "message": "Parse Error"  } }

The nlapiRequestURL call is being made in the POST part of the script.