I always keep two sets of profile and they are not link to each other.
For example, on HubPages I do not disclose many personal information because I believe that the purpose of my HubPages account is to share information with other, and that my personal information are really not important under such circumstances.
On the other hand, my Twiiter and Facebook accounts include many personal information, as they are the platforms I keep in touch with my friends and co-workers. :)
To me, it all boils down to "need", if the need to disclose personal information is legitimate, then I see no reason refraining myself from letting other people to know me more.