IM has already been in corporate America for a while. I've worked for a couple Fortune 200 companies over the last 10 years and all of them (plus the smaller companies) have all had IM. The services listed in the article I've never heard of, but it seems to overlook the already obvious big dogs that have been out there:<p>SameTime. This used to be used when the company was Lotus Notes based.<p>Microsoft Communicator. The IM program that is bundled with the enterprise Exchange and collab tools that Microsoft provides.<p>Skype. For companies that might have a looser network policy, or have to deal with talking to many external clients, this is the easiest way to communicate cheaply, and also has pretty high usage vs something like asking your customer to install and figure out how to use an IRC client.