There's a catch—you share a 14-person van, and it only leaves from designated points in Manhattan, but it's still a pretty good deal considering a regular ride can go up to $100. You book it in the Uber app.
Here's the article (unlocked): https://www.wsj.com/tech/personal-tech/uber-will-now-take-you-from-manhattan-to-laguardia-for-18-65e55247?st=iu5H8r&reflink=desktopwebshare_permalink