There's a good idea buried somewhere in this, but they managed to completely miss the mark.
1. It needs an off-switch (globally and per repo). How did this feature get out the door without that switch? Does Zuckerberg manage product at github now?
2. The data is useless. What does it tell me that ednapiranha "contributed" to X during the last month, without any quantification? Nothing.
3. The data is useless. For most people the "popular repositories"-box shows 5 popular projects that they have forked...
4. The data is useless. When I want to see what a user (or myself) has contributed to then I want to see all of it, not the last 1 month.
Github appeals to the self-improvement, tomato-timer, fitbit crowd here. Those people will start blogging in no time about how "commit-streak tracking changed my life", from their barefoot standing desks. For everyone else these vanity-stats are worse than wasted space; they are visual noise that pretends to convey useful information but doesn't.