Putting things in perspective:
If @VPG_Printing wasn't on Twitter, would I have ever heard of them? No. There are thousands of printing companies on the internet. It would take an incredible marketing campaign for me to know a printing company name. In my search for business cards I probably would have ended up going with the first link that came up on Google.
Twitter gives businesses the opportunity to do three very important things:
1. Reach out to current customers and be a direct customer service agent to them. See @ComcastCares for a great example.
2. Word of mouth. As most Twitter users know, information can spread rapidly online. Take a look at the latest example from Twitterrank. Now obviously, your brand isn't going to spread rapidly like a breaking news story, but that doesn't mean it won't be talked about. Word of mouth is how I found out about @VPG_Printing. It is how I find out about every new blog I read. It is how I decide if a movie is worth paying $10 to see in the theaters. It is important.
3. Show personality. People love companies that have a real personality. Personality is the difference between talking on the phone with a human customer service representative and talking to a computer that can't understand you. Showing that your company is full of real people who really care is incredibly important.
There are many more reasons to be on Twitter, but those are three of the most important reasons for a company to have a Twitter presence. Laura from @VPG_Printing utilizes Twitter in a very effective way. She shows personality, is an excellent customer service rep, and offers up frequent discounts on products. Some companies get it. Some don't. Not every company should be on Twitter, but for the vast majority that should, an opportunity is waiting for you.