Digital chat started out years ago, almost at the same place, and immediately diverged into two groups. Ubique and ICQ, both Israeli startups that were later bought by American corporations (AOL bought ICQ and Ubique, which later was bought back and re-sold to Lotus, and eventually ended up as part of IBM).
Ubique brought the idea of enterprise PIM server and product, while ICQ brought the same idea to the Internet. In a way both were equally successful, yet ICQ much more famous.
In those days, the difference between the product was pretty straightforward. Enterprise PIM brought security, command and control (always a requirement from CIO's around the world) and the sense of trust - you knew who you were talking to on the other side, and you know that while they (mostly) talked business, they would not be hackers and crackers, or other evil entities.
Public PIM, on the other hand, brought the possibility of connecting to new people, chatting for fun and pleasure, connecting, and getting yourself out there in a way that was never possible before: immediate and easy. You were not required to be technically savvy (like IRC) and you could chat and pass information quickly and easily (much more than email, forums, etc).
The coming of social networks brought some change to that. With the popularity of MySpace and Facebook, and with Facebook bringing the concept of real identity social network to the larger population, and then chatting within your social network, we received a kind of combination between public networks, not related to our business, not controlled and monitored (we hope) in the same way enterprise PIM can (and sometimes are) controlled, with the option of adding people WE choose to the network, and yet - receiving some kind of security and trust - only we allow people in, they are mostly identified by real identities, and with some minor care and responsibility - it's not that hard to identify the hoaxes and fakes out there.
From here, it's not yet decided what will happen. Social networks are going into the organization, enterprise PIM are stepping out. Mobile social networks and chats are changing, creating a new market that also quickly tries to enter the web and enterprise, and vice versa. We hear stories of startups creating 'facebook for the enterprise'. We hear about enterprise social network being hosted and offered to the public and the enterprise at the same time (ning offers something like that). I guess it's the mixup before they all become one big market. Our digital world will be one. What new ideas will come from it?