IM is a must in lots of offices. "Talk about instant messaging and some people think it all concerns teenagers exchanging information about the latest news, trends and fashions online. But instant messaging, or IM, is an essential business tool that has become indispensable in many workplaces. Today, 53 million American adults use instant messaging, and 21 percent of those, or 11 million, use it at work, according to a recent survey by Pew Internet & American Life. Many people like the casual and quick communication that instant messaging provides, said Nancy Flynn, author of "Instant Messaging Rules: A Business Guide to Managing Policies, Security and Legal Issues for Safe IM Communication." "IM is essentially turbocharged e-mail," Flynn said. "It enables you to communicate instantaneously. You can respond to client questions in real time." . . ."