(FORTUNE Magazine) – Talented, aggressive, and ambitious Marketing Guy doesn't get along with his engineers. Why? Because they keep saying no. They insist that the product changes he wants are far too complicated/expensive/impractical to design. He doesn't believe them.

So he downloads--without authorization--a CAD (computer-aided design) file of the part he wants to modify and takes it to a friend who happens to be fluent in the software. The friend demonstrates that desired modifications can indeed be made within required engineering constraints. Said friend then gives Marketing Guy a weekend software tutorial to help him detect engineering obfuscation. Marketing Guy isn't really a design engineer, but now he can play one on PC.

Three days later Marketing Guy's CAD software demo provokes a storm of outrage from Engineering. Technically, Marketing Guy is right, but the overall design situation is far more complicated than what's portrayed in the CAD file. Marketing Guy accuses Engineering of always trying to snow him with technology. Engineering accuses Marketing Guy of being an idiot. The meeting dissolves in acrimony.

This (almost completely) true story illuminates one of the subtler truths percolating through the knowledge-intensive workplace: He meddles; you interfere; I add value. Greater participation, selfless knowledge sharing, and "boundaryless" management are lovely ideals. They even work. But every silver lining has its cloud. The economic benefit of sharing expertise sharply conflicts with the behavioral cost of managing how people actually collaborate.

For years now, technology has been eroding traditional distinctions between expertise and amateurism. Author Kevin Kelly calls this technology trajectory "from pro to Joe"--technology that was once purely the province of the professionals has now been diffused to the Great Unwashed. Buy the right software and you may not really be an expert, but you certainly have the tools to fake it.

Barely five years after Dan Bricklin's invention of the software spreadsheet, CFOs discovered that--like the Colt pistol of the Old West--this software was the great equalizer for budgeters. Suddenly department managers who wanted to preserve their budgets--or extend their domains--were using Lotus 1-2-3 or Excel to turn themselves into financial manipulators.

Desktop publishing swiftly turned lowly report writers into graphic designers; people who once thought Palatino was a kind of horse began to compare and contrast the benefits of sans-serif typefaces. Powerpoint and, more chillingly, Macromedia's Director have transformed executives and salespeople into multimedia artistes who see presentations as their chance to put on a show. Alas, all too often these aspiring Kubricks produce presentations best viewed with eyes wide shut.

One needn't be expert in human behavior to appreciate that most "experts" don't like getting clever advice from "amateurs." Doctors cringe when faced with patients who have overdosed on readings from the Physician's Desk Reference and assorted healthsites.com. But in a boundaryless business, marketing people barely think twice about telling engineering how to redesign a product, and, returning the compliment, engineering doesn't hesitate to tell its marketers what product features merit the most promotion. Indeed, global corporations are spending billions building internal networks to facilitate precisely those kinds of communications.

No imagination is necessary to predict that when an organization posts the latest iteration of a product design--or service enhancement--on its intranet, all kinds of people will want to annotate it with their own ideas. Instead of the trusty but physical suggestion box, digital technology enables the suggestions to be virtually modeled and simulated for all to see.

The frightening reality is that tomorrow's engineering software may become user-friendly enough that marketers and finance people can make suggestions that trained engineers have to take seriously. That digitally mediated business processes could be edited or enhanced by almost anyone in the organization--in the interests of "participatory" management--seems more plausible today than at any time in the history of business. Post-industrial management thus must navigate between the Scylla of "Knowledge is power" and the Charybdis of "A little learning is a dangerous thing."

It's no longer clear what "expertise" and "professionalism" mean in this kind of environment. What is clear is that the ethic of boundaryless participation, combined with technologies that can make mock professionals of dedicated amateurs, is going to pose a management pain-in-the-butt for people who like to think of themselves as "real" experts--and who have the skills, experience, and successes to prove it. Digitally endowed dilettantes, in other words, are looking over your shoulder, and they want to help. Honest. Are you one too?

MICHAEL SCHRAGE is a Merrill Lynch Forum Innovation Fellow, a research associate with the MIT Media Lab, and author of Serious Play. He may be reached at michael_schrage@fortunemail.com.