[f_allwein]

True, that is not really covered in this scenario. Except Blogger gives you an option of whether or not to list your blog on search engines. I have a privat blog from before the FB era that is not listed, and does not show up on Google searches for my name. Although of course, I would not put any confidential information on there.

[amelius]

Well, of course it should allow my friends to search my blogs . Just not the rest of the world.

But I guess that if Blogger would be "open", so that other search engines could also index those blogs, then this whole scenario would not work (malignant search engines could expose everything to everybody). So my suspicion is that it would actually be quite hard (or at least require more research) to make an "open" version of facebook.

[ethbro]

The original post misses the visibility point.

To me, Twitter benefits from being public discourse and an open forum for replies. On the other side of the coin, Facebook benefits from being a private forum (as most people use it).

Solutions that don't facilitate these use cases aren't going to be successful. Understand why people chose the services they did (discounting network effect) and then try and build something to compete.