Takei is not only a star of the original Star Trek series, but something of a social media phenom, having just authored a book collecting his online musings.
Here's the official description for the event, which you can join on Facebook:
JJ Abrams is a filmmaker whose work, on both the small and big screen, has been shaping our culture for decades. On May 10th 2013, just days before Star Trek Into Darkness opens in theaters across the globe, the acclaimed director visits the Facebook Headquarters in Menlo Park along side his friend Andy Samberg to answer your questions live. This is an exclusive opportunity for Facebook fans to ask anything about the Star Trek universe, and to boldly go where few have gone before. Who knows, maybe even Sulu (George Takei) might beam in for a guest appearance.