hmmmm... maybe this, and the growing popularity of DJ nights over live music at places like the Black Cat, is all just acknowledgement of the fact that hardly any rock/pop music being made today is truly new or original. It's all just twists on stuff that's come before, and some of the twists are more clever than others.
and actually, even mash-ups aren't entirely new... there was this Europop group in the 70s called
Stars On which did disco-ized medleys of Beatles songs which I think may qualify as early "mash ups."
