One Address Book?

I have an address book on my phone, that I update with people's numbers when I get them.  It syncs to my laptop's address book, but that stops there.  I tried using Plaxo to sync that with other machines, but I wasn't thrilled with their service; I wound up moving my primary email to Gmail instead.

Now, I also have useful contact information at work, in LinkedIn, and in Facebook.

Is there any good utility to tie these together?  Or at least to tie Gmail to an iPhone in a sustainable, low-maintenance way?