Yes, it's fascinating and filled with unverifiable data. I ran into this on my trip to the Grand Canyon last year. Our guide recounted all manner of dire Hopi predictions and then blurted out that due to some type of miscalculation, the Mayan "end-year" was really 2003 and not 2012. I'm not sure who is guilty of the miscalculation though, take your pick of the Mayans, the Sumerians, the Hopis, Art Bell,Sylvia Brown...
I always knew Velikovsky was right, Carl Sagan was a rat for shooting him down...