Twitter has acquired media sharing startup Posterous. Financial terms were not disclosed but Twitter said that Posterous engineers, product teams and other executives will join the company. The Posterous service enables users to share photos, videos and text updates with friends and family by creating private or public Spaces. Consumers can also broadcast content to social media platforms like Twitter, Facebook, Flickr and YouTube. Posterous offers native mobile applications optimized for Apple\'s (NASDAQ:AAPL) iOS and Google\'s (NASDAQ:GOOG) Android. Twitter confirmed the Posterous deal on its blog. However, the future of Posterous as a standalone service is uncertain: Although Twitter vows Posterous Spaces will remain up and running without disruption, the Twitter blog adds \"We\'ll give users ample notice if we make any changes to the service. For users who would like to back up their content or move to another service, we\'ll share clear instructions for doing so in the coming weeks.\" Earlier this year, Twitter purchased Summify, which aggregates key updates and announcements within users\' social network timelines and delivers summary accounts via mobile app, email or the web. Summify disabled new account registrations immediately after closing the deal, indicating it eventually will shut down the product completely. When Twitter scooped up mobile security and privacy solutions firm Whisper Systems in November 2011, Whisper\'s RedPhone and FlashBack services went offline as well. Twitter now boasts more than 100 million active users worldwide, 55 percent of whom are active on mobile devices. According to the Pew Internet Center, 13 percent of adult Americans who go online are on Twitter.