Shel Israel’s Twitterville gives an entertaining fly-through of the world of Twitter, from the beginnings of the service to its current state as a real-time news service for millions. Israel also profiles several businesses that have engaged customers on Twitter and their successes and failures there.

There are three key lessons that stand out from Twitterville: businesses need to respond to customers, acknowledge their problems or inquiries, and offer to help. These would seem to be elementary lessons for any business with customers, but Twitter enables this conversation to happen almost in real time, forcing businesses to be nimble and to speak to customers in the channels they prefer.

Responding to the customer need not be a difficult problem. Customers want to know that they’ve been heard. They don’t want to be referred to a phone tree, left on hold, or placed in a circular bin along with their paper-based complaint. Twitter gives customers a great way to ask directly to be heard — and companies that listen do better in Twitterville. Note that these companies don’t always offer to solve the customer’s problem immediately, but they listen, and respond appropriately. Some companies choose to do this from a corporate Twitter account; others, like Best Buy, coordinate the efforts of hundreds or even thousands of company representatives like an old-fashioned telephone company switchboard.

Acknowledging the customer is a powerful way to get the customer on your side and to turn a potentially negative conversation into a potentially positive one. How many times have you wondered how to get in touch with a large company to share your opinion (and be heard), only not to know where to ask the question? Twitterville gives you a way to ask that question. Companies that listen (zappos, comcast, and others) get a head start on their ability to solve the problem, and offer a venue for customers to ask questions that other customers might be able to solve.

Finally, offering to help brings the customer on your side. If you’re a patient at Swedish Hospital in Seattle and highlight an inefficiency in the way the hospital works from the patient perspective, expect a reply. Not only will you get a response that demonstrates that there’s someone there who listened, but you might also be responsible for improving the ongoing processes of the hospital. All the comment cards in the world didn’t have such a direct response as that.

Finally, the bonus lesson to be learned from Twitterville is that help can be local or global. In Twitterville, the offer to help might be as simple as a link to the right online resource or it might be a crowd-sourced effort to raise funds for charity. Twitterville takes Howard Rheingold’s concept of Smart Mobs and makes the ability to ask a question, get an answer, and rally people to action a reality. In Twitterville, you never know when the customers of today might be the advocates of tomorrow. So make sure you respond to the customer, acknowledge their issue, and offer to help. You might be on the other end of the Tweet tomorrow.