The situation's better than you think, and IM can be a valuable tool for use inside corporations. There are two main open-standards-based approaches for IM, SIP and Jabber, and most of the big IM providers are using one or the other or planning to transition to them. Corporate IM solutions support the security and auditing capabilities using those protocols, and some of the external services do as well. In addition to gateways to cellular text messaging, there are also IM clients for data-enabled smartphones. So the tools are there, and the security's there.

Whether IM is beneficial to work environments is a separate question. I'm also an old guy, and I've used email for almost 30 years, never did much with IRC or MUDs before the current IM systems got popular, and only used AOL instant messaging systems to play with gateway systems. It's even more of an interruption than email. However, IM is less of an interruption than a phone call, and I work in an environment where we're often on the phone, either with customers, listening to training calls, or in other meetings, and IM is a really valuable adjunct to other communications. The presence server provides some hints about peoples' availability, and it's possible to carry on sidebar discussions during meetings, or ask questions of a training presenter without interrupting things.

Also, Microsoft is incorporating presence servers into their mail systems, along with SIP Voice support, so if you're in a Microsoft email environment you'll have IM soon anyway.