The powerful messaging integration is one of the best features of Windows Phone and an alleged screenshot from the upcoming Tango update shows Skype and Google Plus integration into the messenger hub.
After Microsoft's acquisition of Skype, it was pretty clear that we'll see Skype added to WP7's arsenal but everyone expected that it will take until the next major version, Apollo, before it appears. This screenshot (if it turns out to be real) shows that the integration will happen sooner and will add Google's social network to the mix.
The people who took the screenshot claim to have running Windows Phone Tango and say that text chatting over both Skype and Google+ works well, but Skype voice calling needs work. Video calling through Skype will work too, Google Plus Hangouts (that's their video calling service) might not be ready for Tango.
Of course, Windows Phone screenshots are really easy to fake, so take this with a pinch of salt. And we're still not sure when Tango is coming, all we have is a leaked roadmap that says Q2.
Source (in German)