Photo-sharing app Instagram has announced that it now has 80m users, up from 30m in April of this year. That’s startling growth for the app, which Facebook agreed to acquire for somewhere north of $1bn earlier this year. “The combination of Android and network effects as more people use Instagram mean that we’re able to grow faster now more than ever,” says founder Kevin Systrom. However, Instagram appears to have fallen out with Twitter: the latest version of its app, has disabled its feature to follow friends who are already connected on Twitter. Instagram says that Twitter has stopped it from doing so.