When I'm thinking of describing something new to somebody who has not heard of it before, I tend to relate it to something known. For Biznik, the 800lb gorilla is LinkedIn, when you think of online business networking, you think LinkedIn (unless you are apart of the Biznik community!).
Biznik is not LinkedIn, to me, Biznik is more "real", meaning it's more than just an online connection and a profile, it's a way to blend online activities with real life. When I talk to people that are on LinkedIn, the overwhelming majority respond "I have an account but I don't use it", or something like that. Biznik users, on the other hand, use it far more often.
I think a lot of what Biznik is has to do with the actual community itself. They are all "solopreneurs" or "self-employed", so they are using Biznik as a tool as opposed to just having a profile and connections.
So back to the original question, how would I describe what is going on here? Well, it's a better LinkedIn, and the community uses it to enhance their business...it's difficult to break it down to a phrase, and I'm terrible at this, but here's my attempt: "enhancing(ed) business networking". Just some food for thought...
disclaimer: I have used LinkedIn and have found it useful to some degree; it has it's place. I just like Biznik a lot better and have found IT to be much more beneficial to my buisness.