zett - 7:11 am on Feb 14, 2010 (gmt 0)
We have so many confusions as to what "opt-out" or "opt-in" means
You are right.
"opt-in" = Actively confirm that you want to use a certain product or service, to become part of a community, or to allow a certain content object created by you to be used by someone else.
"opt-out" = "opt-in" by default, i.e. it is assumed (without active confirmation by you) that you want to use a certain product or service, to become part of a community, or to allow a certain content object created by you to be used by someone else. In order to reverse this assumed choice, you have to actively revoke the assumptions made by the party who opted you in by default.
Google knows very well that -in theory- they have the audience to create stellar products. They have the eyeballs in their search engine and other services. They could put in ads to promote new products and services (and sometimes they do). But they also know that -especially for social networking services- they need to have the critical mass right from the start to overcome the hen-egg problem (users don't sign up because there is no activity; there is no activity because no one signs up).
As noticed elsewhere on this board, I think Google is increasingly desperate to find the next golden goose. This is one more proof.