I feel like if you apply the same stringent measurement you'd apply there to any other social apps, you'd still find that facebook is still leading the pack...

I feel like if you apply the same stringent measurement you'd apply there to any other social apps, you'd still find that facebook is still leading the pack... The definition of an "active user" can get pretty contentious, but let's just say it's someone opening the application at least once in a month (which is a pretty ridiculous metric but works as a baseline) -- FB is in uncharted territory.