Fourth revival of ska music (the original being in jamaica in the late '60s, second wave or two-tone surfaced in the late '70s, and third wave hit in the late '80s and early '90s).
Many claim that the fourth wave is imminent, ready to appear anytime between now and the early 2010s.
Others claim the 4th wave is already here, heralded by Tomas Kalnoky's band Streetlight Manifesto and side project Bandits of the Acoustic Revolution. (There is a streetlight manifesto song titled "riding the fourth wave")
While some people are excited about the fourth wave of ska, others worry that ska is too diluted and growing farther from its roots.