That's not quite correct. It is no longer visible on the website itself, or within the mobile clients. But if you inspect the requests, you can still see thin

That's not quite correct. It is no longer visible on the website itself, or within the mobile clients. But if you inspect the requests, you can still see things like source: <a href="http://twitter.com/download/iphone" rel="nofollow">Twitter for iPhone</a> which shows the tweet was posted from iOS.