When Twitter changed its usage terms over a year ago, support for the service in Windows Live was pulled. While it has been established during Mobile World Congress 2011 that Twitter will be integrated into Windows Phone "Mango", there's no word about a return to Windows Live. But there's now evidence to suggest that it's about to, as pieced together by LiveSide.net.
When "damaster" of LiveSide.net tried to add his Twitter account when setting up the beta version of Windows Phone "Mango", he was presented with the message, "“to add Twitter on your phone, you’ll need to connect to it to your Windows Live account”.
He also pointed to a tweet from CNET blogger Manan Kakkar who was told during a Mango press event that Twitter "will make a come back to Windows Live (web) with Mango, will have reply_to & other twitter features".
It certainly looks like Twitter will return to Windows Live by the time Windows Phone "Mango" ships.