I think it's value is you are able to be found be those looking to employ you. If you don't want to be offered employment, I don't see a point in having a LinkedIn - a resume does just fine when you are looking.

But this goes towards the GPs post, it is public information. I also deleted my LinkedIn awhile ago. In my opinion a company or person should only be given my CV when I offer it to them.

In terms of a work-circle rolodex, this is odd to me. If I want to keep in contact with the person in the future I will have their personal contact info and keep in touch, otherwise not.