'Daniel Drezner had been an avid reader of blogs since the 1990s, when the now-ubiquitous online soapboxes appeared. But it wasn't until 9/11 when everyone started talking about international politics that Drezner, a specialist on the subject and at the time an associate political science professor at the University of Chicago, weighed in.

As well as wanting to give a "nuanced" expert opinion amid the clamour of amateur punditry, Drezner conceived his blog as a "pedagogical exercise", an experiment in "talking about international politics to an international audience", that he might later write up. But danieldrezner.com took on a life of its own. "A lot more people read it than I had expected. Within six months, New Republic called [about] an online column and The New York Review of Books [approached], wanting me to do reviews."

Today, his blog carries adulatory blurbs from the likes of Sunday Times columnist Andrew Sullivan, it logs some 4,000 visits a day and its author is newly ensconced as associate professor of international politics, with tenure, at Tufts University.

But along the way Drezner's blogging has been held partly responsible for his being passed over for tenure at Chicago last year, despite previously rapid career advancement and a sterling publishing record, and held up as a salutary example of the perils of the medium for academics. He says part of the problem is academic snobbery. If the blog gets lots of attention, the attitude is "who are you as a junior academic to suddenly be capturing more attention than your senior, better published, more prominent colleagues", even, he says, "if they can't write their way out of a paper bag".

But Drezner is not bitter. Academic hiring decisions can be murky at the best of times, he observes, adding that he doesn't think the blog was the only factor. He has moved on.

But in June the blog issue resurfaced with Yale University's decision to turn down University of Michigan history professor Juan Cole for a Middle East studies chair. Yale Daily News said he had been recommended for the post by two faculties, but because of some of his blog entries The Wall Street Journal had branded him a "notorious anti-Israel academic" and cast aspersions on his seriousness as a scholar because of the time he supposedly devoted to blogging. Both Yale and Cole have refused to comment.

Unlike stamp collecting and other inconspicuous hobbies, a blog has high visibility, says Drezner. These days he counsels against blogging under one's own name if you don't have tenure.

And many seem to agree - a rash of anonymous academic blogs have recently appeared. In his discipline alone, says Mark Thoma, associate economics professor at the University of Oregon, there are at least four anonymous bloggers. One, General Glut, comments: "I'm up for tenure next fall - with the example of the untenured (and recklessly not pseudonymous) megablogger Dan Drezner looming ominously." Thoma, who runs a blog, thinks the web soapboxes aren't central to hiring decisions but, if there is a close decision on who to appoint, it might make the difference. "The big issue is time away from academic work. If they want to use that against you, it's sitting there."

Much may depend on individual institutions' attitude to blogs, though. Many academic bloggers are clustered around certain institutions. Margaret Soltan, associate English and human sciences professor at George Washington University, who blogs on "American university life" at University Diaries, says her campus "seem[s] to have quite a lot of bloggers". This makes it "much easier to think in terms of blogging as an extension of one's already established commitment to public discourse".

The nature of academic appointments makes blogs fair game for hiring committees, says J. Bradford DeLong, economics professor at the University of California, Berkeley, who is author of the popular Brad DeLong's Semi-Daily Journal. "You're hiring a colleague for up to 40 years. You want somebody who will do very good work, have a positive influence... and increase intellectual diversity. Their web log is relevant."

While blogs may be risky for authors, those who are written about could also be in hot water. Indeed, blogs have been implicated in the downfall of two US college presidents. Last year, an anonymous blog began running stinging criticism of the leadership of Uma Gupta, former president of New York's Alfred State College, by disgruntled staff. She resigned last June.

Benjamin Ladner was fired last October from his job as president of the American University after revelations that he had made extravagant expenses claims. Before his dismissal, he had been trying to shut down a student blog on benladner.com, which was devoted to exposing his alleged high-rolling lifestyle.

But both cases owe more to poor management than the power of blogs, Soltan says. "The airing of what sound like legitimate complaints against a not very good president and the president's threatened and inept response... could have happened via any number of other media - a newspaper, a list serve, even instant messaging," she says.

Despite lurid headlines such as "Attack of the career-killing blogs" in online magazine Slate.com, Soltan and others point to the advantages of blogging. As Drezner's experience shows, it can be a vehicle for professional, if not necessarily academic, advancement. Thoma says that, on the strength of his blog, he got commissions from The Wall Street Journal to write online columns. "It's not a voice I'd have had otherwise," he says. Moreover, blogging can be more than an extracurricular project. Drezner's blog has thrown up leads for his academic work. A draft for his forthcoming book All Politics is Global, which he posted on his blog in 2004, drew a response from an economist that included "very valuable comments".

Ultimately, Soltan says, "all the bloggers I know of who are rumoured to have had trouble with appointments because of blogging landed on their feet, big time". Drezner, for example, believes that, although he applied for his current post at Tufts' Fletcher School of Law and Diplomacy before the Chicago furore, his blog may have given him an edge.

"It might have played a small positive role," he said. "This is a professional public policy school. They liked the fact that the blog made me a higher profile applicant."'