Google+ and Privacy

Love what I see from Google+. The problem I see from Google all revolves around the issue of personal privacy. Can we make on-line information private? There are, different definitions of privacy. Some/all information will be kept in corporate databases - but who will access this information and how? I don't care about advertising/market research. I do care on "unauthorized" people being able to search or query the data for my personal information.

There are several levels of privacy:
1. Companies using the data for market research
2. Companies advertising goods and services
3. Individuals researching you and finding "unauthorized/private" data
4. The government researching you / keeping dossiers.

All I have to say is:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated ...
4th Amendment to the US Constitution

This YouTube video is an excellent introduction to Google+.