These are just rumors yet, as we have witnessed just a screen-shot of the Tango which boasts of the Skype & Google+ integration in its messenger hub, but we all are aware of how easy it is to fake a Windows phone screenshot. The people who allegedly claim to have taken this screenshot say that they have running Windows Phone Tango and text chatting on both G+ & Skype works well. The video calling feature of G+ (Hangouts) won’t feature in Tango maybe, but video calling through skype will work though voice calling will need some work.
So to sum it up, all this merely depends on whether the screen-shot is real or fake, and there is also no official news yet when the Tango is releasing.