That's crazy that I never heard about it. Is it a recent thing? Very cool that it has taken off regardless, and I suppose serves as a proof of concept for Lyft/Uber.
Given that, I doubt Lyft (marketed towards urban millennials who have smartphones and are cool with riding around in cars with mustaches) and Slugging (mostly used by staid, middle-aged, middle-income workers) are going to compete with each other.
(Still kicking myself for not finishing that app for Slugline-like ridesharing 6 or so years ago :) )