Saul Hansell has a tantalizing tidbit in today’s NYTimes, a report that Yahoo! and Google are thinking about making their email systems ‘more social.’ “Web-based email systems already contain much of what Facebook calls the social graph — the connections between people. That’s why social networks offer to import the e-mail address books of new users to jump-start their list of friends.” Our personal email applications should keep track of who is most important to us, and let us know when those messages arrive.

Saul’s report opens Pandora’s box about the future of Enterprise 2.0. The dirty little secret is that our e-mail in-boxes track our social networks by default — who we communicate with, when and in what order can be as interesting as what in fact we say (or do not say). Our personal address books are more than a random list of names — they’re the ‘black books’ that contain the people with whom we’ve exchanged messages in the past, or want to communicate with in the future.

We intuitively track our business networks through our use of email — the names of folders we use when filing messages, the subjects we attach to messages, and the threads of a back-and-forth discussion are all grist for the social networking mill. Gmail, for example, collects message threads into a single record. This is a handy innovation, which helps to cut down on the message clutter that’s so prevalent in Notes Mail & Outlook.

The real challenge is that messaging inside the enterprise is frozen in time — captured by the two most widely deployed messaging applications, from Microsoft (Outlook/Exchange) and IBM (Lotus Notes). It’s hard to believe that these are legacy platforms.

We need to rethink what else we can do with email inside the enterprise — Lotus Connections goes a long way towards staking out a few essential services. These include an “intelligent” enterprise directory & a tag cloud that relates to communities within the enterprise.

We need to do a lot more with features around privacy, security, organizational boundaries, and context.