You're getting a lot more when you're paying for it, from security guarantees to interoperability with other applications, technical support and increased functionality. The use of IM applications appears to be creeping up on companies as workers download free consumer-oriented software for an unclear blend of personal and business use. It's a grassroots phenomenon. They're using it to communicate externally with business associates or fellow employees on the road or family and friends. People everywhere are trying these services, then demanding that companies implement instant messaging internally.
Instant messages introduce many of the same problems that email does.
Not only can instant messages harbor viruses, but they are efficient conduits of information that can cause legal headaches for a corporation, including the divulgence of trade secrets or the exchange of libelous or harassing statements. But the nonstandard nature of IM technology means it's difficult for IS managers to account for it. You'd prefer that it come through on a standard port. Firewall administrators are loath to open up to nonstandard protocols. With the recent release of Jabber 1.7, for the Windows operating system, the company lets its users encrypt messages both when they're in transit and when they're logged on to the sender's or recipient's computer.