Just a quick follow-up to my earlier post on Salesforce.com to say that Noel Franus (a blogger at Sun Microsystems) points to a new article by no less than Clayton Christensen that has similar sentiments, published in the new issue of Harvard Business Review. Christensen and his co-authors urge marketers to stop focusing on demographics and psychographics, and focus instead on the "jobs" that products do, since these may well cut across customer types.
Marketers have lost the forest for the trees, focusing too much on creating products for narrow demographic segments rather than satisfying needs. Customers want to "hire" a product to do a job, or, as legendary Harvard Business School marketing professor Theodore Levitt put it, "People don't want to buy a quarter-inch drill. They want a quarter-inch hole!"
(I've always loved this quote but never known who said it, great to have the attribution finally.)