At last year's Measurement Summit put on by the Institute for Public Relations (Measurement Commission), attendees, this PRopenent/PRomulgator included, took in a presentation by Dr. David Michaelson and Dr. Don W. Stacks citing research (the first in a series of more complex projects to follow) that sought to address the on-going multiplier agonizer. Bottom line? That product-related editorial coverage does not have any more effect/credibility than advertising. Good news or bad news depending on how you look at it.
It'll be interesting to see how the more complex iterations of the on-going research project shape up and the debate that it will, no doubt, spur.
By the researcher's own admision however, if memory serves, results won't neccessarily apply (consistently if at all) to all communications situations and across all media and that is what they will be testing going forward. So we may eventually abandon the multiplier idea altogether or we may even see different multipliers for different situations (issues vs. product among many others) and different media. That'll get interesting.
Does it simplify, put to rest or further complicate the myth o' the multiplier? Not an easy answer but I'm thrilled that experts are looking at it and can't wait to see the next wave of results.