FORTUNE — Talk about a tough gig: The average tenure of a chief marketing officer — the corporate executive charged with branding, communications, and other activities — is less than four years, in large part because of the increasing complexity of the job, says executive search firm Spencer Stuart.

Yet that complexity, fueled by new technologies such as social networks, is exactly what makes this a great time to be a marketing chief, says Peter Krainik, founder of the CMO Club, an industry group. Gone are the days when business just pushed out messages to consumers. In the age of Facebook and Twitter, corporations can have a two-way conversation with customers, a prospect that is exciting (and scary) for marketers. Layer in the global nature of the job (imagine branding a product or a company in 180 countries) and one can see why today’s chief marketing officer needs to be a creative, tech-savvy internationalist.

In our next issue Fortune will unveil its Executive Dream Team of corporate all-stars. Which CMO will make the cut? He or she will surely possess the following skills:

They rally the troops

Thanks to the Internet, marketing now cuts across the entire organization, from customer-service reps responding to complaints on blogs to the IT department, tracking consumer web behavior. CMOs have to train every employee to be an ambassador for the company. In 2009, Best Buy (BBY) CMO Barry Judge created the Twelpforce, which allowed any employee to handle customer service or product queries via Twitter.

They’re futurists

Soon after she became Walgreen’s (WAG) first CMO in 2008, Kim Feil’s research showed that some consumers viewed the retailer as a convenience store with a pharmacy in the back; she saw an opportunity to reposition the company as a premium health care brand, and at her urging the company started showcasing its wellness offerings, including its walk-in clinics. Despite the sluggish economy, revenue has climbed 14% since her arrival.

They’re number crunchers

New business software lets executives track the financial returns of marketing campaigns. Top CMOs pore over these numbers, using the data to bolster ROI. They also view their departments as potential moneymakers rather than as cost centers. At GE (GE), Beth Comstock’s “clean tech” Ecomagination initiative looks like feel-good marketing; under the hood, though, there’s a real business that last year generated $18 billion in revenue.

Examining spreadsheets and empowering customer-service reps may not bring executives into marketing, but those are now roles that CMOs juggle — especially if they want to stick around more than two years.

[polldaddy poll=5346752]

This article is from the August 15, 2011 issue of Fortune.

Editor’s note: A previous version of this story incorrectly stated that the average tenure of a corporate chief marketing officer is less than two years, according to executive search firm Spencer Stuart. The average tenure is actually less than four years.