Weblogs, also known as blogs, are essentially online diaries that can be created and maintained without the need for any web design experience.

The vast majority of blogs are background static to all but the friends and family of their creators, but it is becoming increasingly possible to find blogs that give unique insights into the working life of the authors.

Many "bloggers" write openly about their work, sometimes with approval from their employer. Microsoft is a case in point. About 150 staff author blogs which discuss work-related issues that the company approves of. RealNetworks and Macromedia, internet software firms, also have small teams of blogging staffers. Some firms ask staff to use blogs as a form of soft marketing and "knowledge management" to help customers keep up to date with the thoughts and activities of key members of staff, as well as share developments internally. For example, Jupiter Research and Gartner host weblogs from their analysts on their company websites

Reading their blogs, it is clear that Microsoft bloggers are careful not to reveal confidential information and appear well aware that many of the readers are competitors and journalists eager for insider details. Robert Scoble, a new Microsoft staffer and long-time blogger, is typical. In a recent posting on his blog, he said: "So far Microsoft has allowed weblogging to go on because none of us have done anything wrong yet. Just wait and see what would happen if I started speaking for the 'anthill' (Microsoft) though. Or, if I leaked a Longhorn (the next version of Windows) schedule of build here. Whoa. Then you would see the anthill write some rules really quickly."

UK blogging is so new there are no usage figures available, but an estimated 500 to 1,000 bloggers write regularly about their work. Tom Coates, a London-based freelance web designer, has been blogging for four years and says that none of his employers has ever asked him to stop writing about work or to observe a specific policy. "I think bloggers know that it is about integrity. You know you must not mention anything that is confidential. One blogger I know sums it up by saying 'you shouldn't write anything your grandmother would not like to read'. Bloggers also know that future employers are likely to read what they do."

But Coates admits that some have angered their employers, citing one that revealed details of company redundancies and another that was sacked for publishing offensive comments about colleagues.

Consequently, the rise of "workblogs" is causing concern among the blogging community. There is no legal precedent specific to blogs, but authors of websites that criticise corporations are no strangers to legal action. In France, a court recently ruled that Lucent Technologies was liable for a site created by one of its employees in work time. In a controversial decision, the court found that the site constituted "brand forgery" of the roads authority firm Escota.

Ray Ozzie, the founder and chief executive officer of the collaborative software firm Groove Networks, encourages his staff to use weblogs. He has published his firm's policy on his blog for open discussion.

"We wanted to provide a mixture of encouragement and guidance," says Groove vice-president Jeff Seul, who drew up the guidelines. "Our policy originated because a number of employees started blogs and one of them expressed concerns and asked us to develop some guidelines."

But David Naylor, technology law specialist at Morrison & Foerster, in London, says that employees' use of such technologies can be a substan tial risk to employers: "There is plenty of scope for sites to contain content which gives rise to legal liability, and employers may find it difficult to distance themselves from this risk. The more they authorise or appear to the outside world to authorise such sites, the greater the risk will be."

Naylor summarises typical risks as defamation and intellectual property infringement. But he agrees that guidelines can help: "It's about striking a balance and clarifying the dos and don'ts in a policy document."

To minimise the risk, he recommends that employers set out clear policies that establish their rights and the rights of their employees, as well as obligations in connection with technology use.

Matthew Harris, an IT specialist at law firm Norton Rose, strongly advises companies against encouraging staff blogs: "Some companies do promote employee blogs, presumably as a marketing tool. But a company should think long and hard before going down this route. There is a real and significant risk that it will be held responsible and liable for the content of the employee's blog."

In the light of such warnings, it is likely that many firms will prefer to turn a blind eye to blogs in what is seen as a "don't ask, don't tell" approach. This may reduce liability, but blogging enthusiasts believe it will also hold them back from gaining the marketing, ideas sharing and social benefits that blogs offer.

"I don't think I would work for a company that didn't allow staff to write about work in their blogs," says Tom Coates.