I firmly believe that using uncontrolled urls - such as facebook, g+, etc. - on business cards, print material, or even as your established "online home" is unwise. I think its better to maintain/publish urls originating from a domain name that YOU control...And then create links (with underlying associated metadata "rel=me" style links) or setup redirects...Such as: YourDomain.com/gplus or YourDomain.com/linkedin...etc...

This leaves YOU in control. Can be done on the really cheap. And if google, fbook, linkedin, or any of these services changes things around such as urls, or UI, or ToC, or anything YOU don't agree with, then you kill the redirection/links. Quick, easy and from one central point.

Granted their sites will have a little more SEO juice up front...And, maybe I'm being idealistic, but eventually all search engines will begin to see that YOUR domain is the authoritative point on the web for YOU...and that the start point is YOUR domain not the myriad of social networks.