The Value of #PR. Can it be measured? What to pay for publicity?

Kudos to Carl Bialik at the WSJ for opening the can of worms that many within the "public relations" industry would like to keep closed, particularly those that pitch AVEs (Advertising Value Equivalents) as the metric by which they charge for their services...
Here's the thesis:

For decades, many publicists have translated clients' news coverage into dollar figures, with a simple rule of thumb: A newspaper article is worth as much as a newspaper ad of the same size. Similarly, 30 seconds of television news coverage is seen as comparable to a 30-second ad. 

Some public-relations specialists, reasoning that news coverage carries greater weight with consumers than paid advertising, put a news article's value at three times an equivalent-size ad.

But other public-relations professionals and academics have railed against making these calculations. Publicity, they say, has different goals than advertising and shouldn't be measured in the same way.

This blogger would argue that putting a definitive monetary value on a blurb is bombastic, BUT, the PR hack's job is to get the client as many mentions as possible, whether in major newspaper stories, radio, TV or attributions in blogs. For those that favor a flat tax, maybe there should be a flat fee, or a fee scale that's based on number of third-party mentions, and the scale is limited to media sectors?

What sayeth you? Let us know!