Estimates vary, but the latest numbers from Web analytics company Compete.com put it at 14 million Twitter users per month compared to 91 million monthly Facebook users.

[ Before you decide to deploy Twitter, it's a good idea to consider the security implications. | See how HP and JetBlue are using social media. | And learn InfoWorld's 10 commandments of social media etiquette. ]

However, one area where Twitter appears to be way ahead of Facebook is in business. And Twitter is not alone: Other Twitter-like services, mainly Yammer and  Socialtext, are also making inroads into the enterprise.

Twitter is already in business -- big time

Most people associate the word "enterprise" with traditional smokestack industry giants like Colgate Palmolive, ConAgra Foods, and General Motors -- for the time being, at least. But enterprise companies also include Hollywood studios, all the major news networks, and giant publishing companies like the New York Times and Time Warner, which owns CNN. These non-smokestack enterprises have jumped on the Twitter bandwagon with both feet. InfoWorld has also added Twitter to its mobile options.

The broadcast industry was the first to latch onto Twitter as a marketing tool, helping marketing professionals do something they probably learned in Marketing 101: creating customer loyalty by building a relationship with the consumer. And what better way to build a relationship than to use a tool that lets you have a personal, one-on-one conversation with millions of your customer-viewers simultaneously?

CNN, MSNBC, and Fox make their correspondents and program hosts available via Twitter. Whether or not a tweet (the name for a Twitter message) from Wolf Blitzer really is from Blitzer is beside the point. They are building, they hope, loyalty to CNN and Blitzer as a brand. The harsh reality is this: The next time there's a disaster somewhere in the world, they want you to turn to their channel to hear the full details. How better to do that than if you get a tweet alert from Blitzer himself, saying, "Hey buddy, there's trouble in fill-in-the-blank"? Hollywood has followed suit with fans and stars sending tweets back and forth whether the star in question is on location or out of work.