As I'm studying social network software right now, I consider it my job to try many of the hundred some odd social networks out there right now.
I just joined Zero Degrees, and like many others, it asked me to upload my address book. I've done this before and usually it just finds those who already have joined these networks and links us together. Typically I delete my address book at this point, and don't bother to invite contacts that are not already members of that particular network.
However, Zero Degrees quite obnoxiously at the last "next" button, with no warning, invited everyone in my address book, and thus spamming my contacts. There was no opportunity given to me for it to just search for existing members. I aborted this as soon as I could, but about half of my address book contacts got spammed.
This probably explains some of the invitations that I've gotten from others that I didn't expect, thus I suspect that I'm not the only one that this has happened to.
So my apologies if you received "Yet Another Invite to Yet Another Social Networking Service" from me. I do not invite my collegues to ANY of these social networking services unless they ask me to, or they are already a member.
Thus if you are planning on experimenting with Zero Degrees, I don't recommend that you upload your contacts. I'm going to be a lot more careful with Zero Degrees in the future, and every other new service.