Google (GOOG) on Tuesday announced a save-the-date for its annual I/O developers conference in San Francisco. At last year’s event, the Internet giant announced the Nexus 7 tablet, Nexus Q media-streaming device and the Android 4.1 Jelly Bean operating system. Google co-founder Sergey Brin also demonstrated the company’s Project Glass augmented reality head-mounted display unit with an entertaining skydiving stunt. It is speculated that at this year’s event Google could announce the Key Lime Pie software version of Android and other goodies. Google I/O 2013 is scheduled to take place from May 15th to May 17th in San Francisco. Registration is set to open sometime early next year.