It looks like Microsoft wants to take Apple's Find My Friends head on. According to Spanish-language site Microsoft Place, the company is in the process of developing an app called People Sense, which looks to deeply integrate Bing Maps with messaging and calling features.
Microsoft Place took a deep dive into the most recent build of the app (which is currently codenamed Buddy Aware), and it seems fairly robust. In addition to providing real-time location info for the people you follow, it will give detailed directions to contacts' locations and also have calling and messaging baked right in. By the looks of it, the only thing it lacks is notifications for when friends are nearby, though more features might be on the way.
More features might be on the way
It's unclear when People Sense will see release, though the most recent build looks solid. That said, people might have to try harder to find uses for the app when most people have iPhones and Android devices.