I don't think that this is the same. I can not think of a reason why one should have two Facebook accounts, except for maintaining two complete separate sets of relations, for example for anonymity.

But having several Google accounts can happen much easier, for a variety of reasons. For example, I have used a GMail address for since my teen years. Turns out I don't actually like the format stupidnickname@gmail.com anymore and would rather have something like myname@mydomain.com, but I'd still like to keep the GMail interface. Google Apps is wonderful for this, so I made an account there.

But I can not just ignore my old account, as I still get email sent to the address (I forward it) and I used the Google Talk functionality for my Jabber needs. Also, I bought my first Android apps with my old account, so they are linked to it. That means that I have to use my old account as the first one on any Android device, or I can't download my apps again.

What I would wish for is this: Have services that can be linked to any identifier/email, and shared between any number of them, so I could, for example, have two sets of email (one private, one business), but just one of GTalk, G+, Feedburner and Analytics.

I know that implementing this on top of the current system might be hard. I still think that this is the kind of functionality one can expect from a company like Google, and I would gladly pay for it.