Instagram stayed mum on its current usage figures after its big Terms of Service brouhaha, but it's now finally changed its tune and offered some details on its monthly active users for the first time. According to the company, that figure currently stands at 90 million, a number that AllThingsD notes is actually up ten percent from December to January -- Instagram's Kevin System also tells the site that the company "continues to see very strong growth around the world." As for how active those 90 million users are, Instagram says that they're
