Proof, if any was needed, that 50 years after Woodstock we live in a very different, not-so-Mad, Mad, Mad world.

There has been a lot of wingeing recently about the way the world of advertising is changing. And perhaps it’s evolving even faster than we imagined. Several disparate proofs of this have crossed my desk in the last week:

Consider a report from the Gartner Group predicting that mobile ad spending (worldwide) will grow 74% this year to just under $1 billion and then in 2011 will take off and by 2013 will pass $13 billion.

Can you imagine the trajectory of such a medium? The line on the graph is pointed almost to the vertical.

What is going on to drive velocity-fueled usage? The number of hours people spend on their handhelds is increasing because the new smartphones allow you to do so much: make and receive phone calls, receive and send email, download music and short videos, book a restaurant, check the news, Twitter a friend, check the stockmarket and your Facebook page, surf the Internet and on and on. There are already 50,000 apps for my iPhone. I’m going to need an app just to decide what apps I want.

But in order for this forecast to be realized three things need to happen.

First, the per month usage cost of a smartphone or iPhone needs to come down from just under $100 to an affordable $50 or so a month.

Second, Internet browsers like Yahoo!, Google, Microsoft and AOL need to incorporate new ad formats into their content or open up new templates, that allow people to access ads when they want to without interrupting tasks like Web access and GPS positioning-related activities.

Third, ads either have to deliver a service or product or be so entertaining they rank up there with the best of YouTube.

Meanwhile, the business model for TV, magazines, radio and outdoor will continue to self-destruct and constrict as less and less ad dollars are available to support content—or the content will have to get better, as is happening with the stories in my Economist and New Yorker, to justify a higher sub price for the consumer.

 Old media will be able to find a place in the digital world for some of its content. So Sports Illustrated can deliver scores and player profiles and betting tips. But not long features.

Vogue might be able to capture some readers who want up-to-the-minute celebrity gossip or deals on shoes and clothes between monthly issues. But not long-form.

It’s a digital world. There are still great fortunes to be made. But not in the old way at the old levels. So where does that leave sex, drugs, alcohol and rock-and-roll that used to fuel this industry?

For that we need to turn to that iconic raconteur and culture maven, Jerry Della Femina.. Now, at 73, chairman of what, by my count, is the fourth agency bearing his name, he talks vibrantly, in the August 30 issue of USA Today, about the time when three martini lunches were standard.

He recalls how he and his colleagues at Della Femina Travisano & Partners in mid-town Manhattan would go to the Italian Pavilion (now Michael’s) and, as they walked through the door, the bartender would automatically mix their first round. Everyone would down that, and then as they started to look over the menu, the second would arrive. That would be downed and then as they were placing their lunch order the third would arrive. To me that’s Hunter Thompson’s definition of perfection: drugs are dripped into your system at a constant rate without any need for communication.

As for sex, there was always lots of that going on. Della Femina says the agency even had an “agency sex contest” at the end of the year, where in a blind vote, the winning couple would get a weekend at The Plaza Hotel.

“Nobody drinks or screws around like that anymore,” says Della Femina who today is chairman of Della Femina/Rothschild/Jeary and Partners. “It all stopped [by the mid 1980s] when the financial guys took over. Maybe agency chairmen can still drink, but not the soldiers. Today it’s about people looking at the bottom line. It’s changed as a business. Mad Men is celebrating a time that no longer exists.”

Today, all the license for abuse that was underwritten by the 15% commission is gone. But there is still room to have a lot of fun in advertising and publishing or broadcasting, and I know a lot of people who do. Jerry Della Femina thinks it was “the financial guys” who ended the Bacchanal. I think it just ran its course and now all things digital are forcing on us a new communications model for a different age.