It has been announced on Mashable that Twitter has invited a select group of users to test its new analytics system.

Such a service has been rumored for some time now and it was hinted by a Twitter executive earlier in the year that Twitter analytics should roll out by the end of 2010.

The official Twitter analytics service will measure data including; which tweets are most successful, which tweets caused people to unfollow, and who the most influential users are that reply and retweet their tweets.

This news will come as a massive blow to the many third party Twitter analytics vendors, who’s tools, until now, have until now been used by millions. However, none of the services have been particularly brilliant and have raised questions about report accuracy.

The ‘official’ Twitter analytics system will be extremely useful for Twitter users everywhere – particularly for brands and businesses who rely heavily on the interaction of their followers. Imagine the benefits of being able to see how your followers react to certain tweets and which of your followers are your best brand advocates.

We’re keeping our ear to the ground for further announcements, so stay tuned.

Well done, Twitter – you got there eventually.