The Tango video calling application has surfaced on the Marketplace today, finally giving Windows Phone users the ability to engage in video conversations like (and with) their counterparts using iOS or Android. Free calls can be made between devices running those three operating systems, as well as Windows PCs, though to get the full experience you'll probably want to make sure your phone has a front-facing camera. Another requisite is that you're running Windows Phone 7.5, or Mango, which Microsoft has been rolling out to its full portfolio of WP handsets.

Tango's arrival in Microsoft's app store keeps up the company's torrid pace in expanding the selection of apps it offers, following the recent debuts of the Nokia Maps and Spotify applications. The most awaited Windows Phone app is still arguably the dedicated Skype client — which should give us an idea of why Microsoft felt so compelled to buy Skype — but until then, the Tango app will at least provide some functionality for eager video callers. Let's just hope it doesn't confuse too many people into thinking that Microsoft's next OS update, also dubbed Tango, is now out and about.