We know that Twitter integration is going live with Mango. Well it looks like the social side of Windows Phones isn’t going to stop there. In a tweet, Ken Dacey states that he’s testing checking in using a Windows Phone. And the method is noted as “Windows Phone(via WindowsLive)INT” which redirects you to the Windows Phone website. To be clear, there are other people on Twitter using this same method of Tweeting (Windows Phone(viaWindowsLive)INT) like @stephensisk and a bunch of others (like that Twitrtestuser2Twitrtestuser4richz98052CNeesh) which all leads to: @twitWL which appears to be the main tester that they are using here.
So what’s this all mean? Windows Live is likely going to get Twitter natively (just like Facebook is) and that will include check-ins (that are likely going to let you choose your method of check-in but we’ll have to see how that works). And just like it does for Facebook, that means it will flow from Live (the website) to your Windows Phone.