AdDuplex has its latest round of Windows Phone data available, painting a broad picture of the current state of the WP market: which devices are most popular, where, and which carriers have the largest Windows Phone user bases. While the overall picture isn’t very surprising (Nokia dominating with HTC picking up the slack), one juicy little tidbit did surface while data for the report was tallied, revealing a previously unknown Nokia handset. Nokia model RM-877 appears to be preparing for a launch on AT&T. The ...