When popular new media formats emerge it usually doesn’t take long for advertising to follow, so it’s not surprising that the rapid proliferation of Web logs – a.k.a blogs – is establishing a new advertising marketplace.

Blogs, online’s niche media format du jour, are chronologically structured logs of text and images published to the Web with easy-to-use software tools. The segmentation and abundance of blog content (think anything from the naval-gazing minutiae of a teenage girl’s life to the practical punditry of a tech firm CEO) is fueling a new form of online advertising.

“Everybody needs to do a bit of guerrilla marketing, and blogs qualify as that,” asserts Henry Copeland, CEO of Blogads, a blog-exclusive ad network launched in August of 2002 by newspaper and magazine website publisher Pressflex.

The American Civil Liberties Union, pop artist Coop and spam blocker Messagefire have placed ads on the network’s blogs. Advertisers buy sponsorships of specifically chosen blogs for blocks of time rather than on a CPM basis, and ads can be updated regularly.

But advertising on blogs isn’t for everyone, cautions Todd Copilevitz, director of Richards Interactive, an agency that’s developed blog marketing strategies for Nokia, Home Depot and, most notorious, Dr Pepper’s flavored milk drink Raging Cow. “If you want the steady drumbeat of sell, sell, sell, buy, buy, buy, this is not the forum for you. You do not control message.”

The agency first began using blogs as ad medium nearly two years ago. Richards now has a blog network that can be used spur viral buzz for its advertisers. One recent effort, for example, helped launch the Nokia 3650 camera phone. The authors of carefully selected photography-focused blogs were given the camera phones in the hopes that they would discuss their opinions of the product on their blogs. The tactic worked.

“We wanted to hear from people what they liked, what they didn’t like and how their friends reacted to it,” notes Copilevitz, “It’s often the little things that click-in with consumers.”

The Holy Grail for many marketers is to get a discussion their brand going among influential consumers but the uncontrolled nature of blog communications may not be for the feint of marketing hearts.

“The problem with blogs is that with some free-form input from users we’re not able to have content control,” contends Jeff Hirsch, chief revenue officer of ad network Fastclick. The company doesn’t include blogs in its network of sites, all of which “undergo a rigorous editorial review process to ensure that the content and demographic of the readership is appropriate.”

When Richards attempted to monitor blog content written in conjunction with the launch of Dr Pepper’s Raging Cow beverage, the tactic inspired hype, but much of it negative. Dr Pepper got six influential blog authors to agree to promote Raging Cow in their blogs without disclosing their affiliation with the company. When they discovered the stealthy nature of the effort, some members of the blog community who consider honesty and integrity to be integral to the blog medium, called for a boycott of the product.

Despite the risk of being affiliated with inappropriate content, numerous advertisers have run ads within Google’s AdSense network, which includes blogs. The contextually driven system places ads on pages based on what it perceives the site’s subject matter to be.

Michael Zimbalist acknowledges that AdSense advertisers, whose ads appear on blogs, are achieving reach. Still, the executive director of the Online Publishers Association contends, “It’s not clear what you’re buying if you’re an advertiser. There’s not a strong identity with where consumers are seeing the ad.”

Texturadesign, Inc., makers of a bag-closing and -resealing contraption called Clip-n-Seal, are willing to risk the possibility of negative portrayals of their brand in blogs. The company was the first to run a campaign through Blogstakes, a sweepstakes service that takes advantage of the fact that blogs frequently link to other blogs. People who linked to the Clip-n-Seal Blogstakes promotion on their blogs automatically won a package of Clip-n-Seals when they referred a winner to the contest.

Within a month, says Texturadesign CEO, D.L. Byron, “thousands” of people had linked to the Blogstakes contest. “The effect that had, is it shot us up to the top of Google’s page ranking,” he adds.

With potential results like these, it’s little wonder blogs have begun to pique advertiser interest.