A couple of leaked screenshots of an alleged Tango build made its way onto Russian site, WP7forum. The site has made mention of a couple of new features in Microsoft's next Windows Phone update, which includes:
Hardware-wise, the Tango phones are said to sport a more relaxed criteria, including a downsized minimum requirement of 256MB RAM and inclusion of 3-megapixel cameras. We are expecting Microsoft to unveil more details of its plans for Tango at MWC this year, with the later update codenamed Apollo scheduled for Q4 this year.
Source: WP7forum via The Verge