This is a Google Sidewiki I wrote about a great article called: Using Twitter for Brands or Corporate Identities by Dawn Foster. I encourage you to read the entire article, as it offers a number of excellent ideas to businesses wanting to incorporate Twitter with their marketing.
The lessons in this article are: Listen and respond to mentions of your brand, don't blast out links to your own content, don't be too promotional, have a personality and follow back people who follow you.in reference to:
"It is OK to link to informational blog posts, but I always put some text around it so that people can decide whether or not to click through. You should also be linking to posts from other blogs that are relevant to your company or industry as a whole. These should be a fairly small portion of your overall Twitter posts"
- Using Twitter for Brands or Corporate Identities « Fast Wonder: Online Community Management (view on Google Sidewiki)