Yesterday Microsoft released to the public "an experiment" socl. It was first run as a closed experiment, and since yesterday it is open to public.
You need a FB or Windows Live ID account to sign up.
As soon as you sign up you need to accept the TOS, just like in any other services. But, two paragraphs caught my attention:
So.cl is an experiment in open search. That means your searches on So.cl are viewable by other So.cl users and will also be available to third parties.
Does not Google+ does something like this? When you +1 in the search results, you are showing the rest your favorites results.
So.cl does not automatically post your searches, comments, or likes to your Facebook stream unless you choose this option. Also, we don’t contact your Facebook friends unless you invite them.
I like this one, it is an opt-in and not an opt-out, like Twitter decided to do.
To me, it looks like Google+, even the front page looks like it.
The features are not really the important point, the real issue is where people is, and that is Facebook. Socl is going to have the same problem Google+ have. It wouldn't surprise me to see socl's features included in Facebook in some weeks.