That depends entirely on where you work and who you work for. Some employers actively encourage staff to discuss work on their blogs, some come down hard on even the faintest reference to working life, and the vast majority sit somewhere in between. Many employers have no clear rules at all, and will only draw some up when they come across an employee blogging about them. If you're going to be that employee, you need to be prepared.
The first step to discovering your employer's position is to check your contract and the organisation's policies to see if there are rules specifically covering blogging. A good policy will be clear about what you can’t put on your blog as far as work is concerned and, however harsh it may seem, you should stick to it.
If there is no specific blogging policy, there may well be one on communications and conduct generally, which is likely to cover most of the concerns employers have about blogging, such as making sure you don't disclose confidential information, protecting the organisation's reputation and use of the internet at work.
If there are no written rules, you have two alternatives. You could continue blogging happily away without your employer's knowledge or approval, but realising that you are risking a harsh reaction if you're found out. Or you can broach the issue with your employers, tell them what you're doing and that you might like to talk about work and asking how you can make sure they're happy with that. They may respond by threatening you with dismissal if you say anything negative about work, or they may welcome the chance to set down some rules that help them engage with a popular phenomenon. Either way, you'll know where you stand.
