This is type of marketing is wide spread. We work with a large software company that employs many persons to post in forums with comments that are pro to their products.
We also work with several real estate marketing companies that have forum auditing software. The software constantly scans web forums and searches for key words based on their current and upcoming projects. When the software detects comments about their projects, it will send an alert. Then, a marketing writer can go to the forum and post comments to either squash any bad publicity or hype any positive.
Despite the forum admin's efforts to prevent this from happening, I wouldn't doubt if this forum has been subject to some of these subtle marketing tactics, or at a very minimum, being monitored.
On a plus note - Check out the truck in the background of this pic -
