As mentioned, most often, corporations do lend themselves to blogs. However, there are a number of considerations.
On the upside, blogs allow for corporations to present information that is current without having to have a full corporate strategy around it. It is, however, a commitment and if you're going to create a corporate blog an editorial schedule should be the first step, detailing anywhere from 15-20 articles or topics before announcing your endeavor.
Depending on the voice for your blog -- Will it be the CEO? Public relations? Marketing? -- there will be different levels of tone, there will also be different levels of response from the viewing, and responding audience. And remember, give someone voice and they're more than likely to use it so be prepared for a response.
A corporate blog gives the appearance of transparency and control. The appearance. If it needs to be vetted by lawyers and every comma and semi-colon, the tone and style will probably reflect as much and your corporate blog runs the risk of becoming the equivalent of Internet birdcage lining. When it relates to how much control you have, bear in mind that as much as you can provide a line to the outside world, so to can others.
Employees blogging on their own time are occurring with increased frequency, detailing not only what occurs by night, but by day as well. If you're concerned about information being released, take some time to search for your company name and anything else that might be a concern.
Which brings us to the last point. Content. Search engines love content. Moreover they love current content. As such, a blog can be an effective tool in staying one step ahead of your competitors in the marketplace. And it can be an effective competitive tool.
Finally, a corporate blog gives you the opportunity to "step up to the plate" during times of crisis or business management. Disgruntled customers or employees can effectively skew public perception but a corporation that shows the commitment and integrity of dealing with issues head on can also affect public perception.
A blog is a commitment. But ultimately you choos how often and regarding what. Be judicious on both counts and bear in mind, once it's out there it's out there so try not to be too out there.
~ The (SEP) Guy