Gartner's Adam Sarner says half of all social media projects underway at Fortune 1000 companies will fail.

Kind of like the old truism about advertising, the trick is figuring out which half is no good.

Caroline McCarthy:

"(Businesses) will rush to the community and try to connect, but essentially they won't have a mutual purpose, and they'll fail," Sarner said. By a "mutual purpose," he means a way to serve both the company putting out the campaign and the audience interacting with it: finding that balance is not easy. The quirkiest and most addictive campaigns often provide little value for the company and turn out to be fads, whereas marketing efforts on the Web often don't go over as well with the public.

Previously: Your Blog Stinks, and Your Online Community Stinks.

Del Monte seems to have the right idea -- its pet-food sites are about cats and dogs and their people, not just Del Monte brands.