The truth is that it's most likely a hoax. Someone tried this once before in 2004, claiming to be the comic actor known for his large-scale pranks that blurred the line between reality and comedy, but Kaufman never materialized. Now someone claiming to be Kaufman is operating a twitter account and answering questions about his planned return. His official site is a bare-bones page promoting The Comedy Store appearance and some unfunny dialogue for a script called "Harold and Marge."
Any anonymous person with a computer could make the claim that they're a deceased celeb come back to life, but the Kaufman hoaxes are unique in that it feels like something Andy Kaufman would've encouraged (check out Milos Forman's excellent 1999 biopic Man on the Moon for a primer on the comic). I can't even begin to guess what, if anything, will take place in Los Angeles on May 16, but to ignore it squashes the winking, playful ruses that Andy Kaufman was so adept at. May 16 is the twenty-sixth anniversary of Kaufman's passing, and if someone wants to celebrate Kaufman's spirit by trying to put one over on me, then I'm an easy mark.