By the power of Google I unearthed a couple of solidly-written and easily adhered-to blogging policies in use by three different companies: IBM, Sun Microsystems and Yahoo. I doubt the fact that all of these IT-related organizations have blog policies is sheer coincidence. I find it more likely that companies with strong tech focuses will obviously confront and deal with upcoming technological trends. Companies with primarily blue-collar workers and those in the non-technological sectors will have less need of blogging policies. Anyway, I'll start you off with a couple of links to check out.
First, Sun's blogging policy, which (as I understand it) was drafted by an employee blogger and then canonized by the company. Sun is of course the distributor of the Java platform. From their website I took this article. Give it a quick look through if you want, but I'm going to highlight the basics later anyway.
Secondly I checked out IBM's developers' blogging policy. Intriguingly the guideline was found within a blog itself. If you care to look at IBM in general, they are located here (go figure.)
Lastly I found Yahoo's blogging policy. Hooray PDFs! Sorry for the inconvenience, I know no one loves acrobat but this is the format Yahoo's distributing it in.
Surprisingly, these policies were not all rule/regulation. In fact, they attempt to motivate nonbloggers into doing so while placing limited restrictions on existing blogs. For example, Sun encourages blogging not for the sake of blogging, but to "become part of the industry conversation." In this case a company views blogging as much a tool of business as of communication. In this area, the companies encouraged employees to "be interesting," "post links," look at already established blogs for help, and to "add value [....] to the business" via blogging.
All three companies had the same basic guidelines when it came to posting. Each made it clear that the blogger must identify himself as an individual independent of the company; the company has no liability for the blogger's actions. Posts should never consist of industry-sensitive information unless discussion in the area is promoted explicitly by the company. The same goes for fiscal reports. All three speak to treating commenters and fellow bloggers/coworkers with respect. Additionally, they warn against not checking your facts; they want their employees to portray themselves as truthful.
Sun addresses potential buyers looking at the critiques a blogger posts about his company's products. They say the worst thing that can happen is "that a Sun sales pro is in a meeting with a hot prospect, and someone on the customer's side pulls out a print-out of your blog and says "This person at Sun says that product sucks."
Yahoo focuses strongly on the legal logistics of blogging, discussing how the PR department must be consulted before talking to the media about a blog. The amount of information a Yahoo employee can blog about is determined by their employee contract with Yahoo.
IBM tries to promote blogging to expand their influence in the industry. It encourages bloggers to talk about what they know and use the practices they learned at IBM thinktank sessions.
Looking at all three, I was able to build my own, rather more succinct "Best Blogging Policies" list:
1. Make yourself identifiably independent from your company
2. Stay in your own domain of knowledge, and speak only truths
3. Keep necessary antagonism "polite" and not ad hominem
4. Keep company secrets secret
5. Don't blog about anything that would get you fired.
6. Make sure your company knows that you blog/get its permission
Following these simple rules will probably maintain any employee-company relationships during one's stint as a blogger.