What is "AddressBookUrlForwarder"?

I'm guessing that this application is used to retrieve Facebook and Twitter contact details for display in the address book.

This assumption is based on release notes for a recent update of Mac OS X, as well as the content of that application's executable (as viewed with strings):

strings /System/Library/CoreServices/AddressBookUrlForwarder.app/Contents/MacOS/AddressBookUrlForwarder`).

The output of strings makes me think that the application is a URL handler for these expressions:

...
_urlPatterns
http://www.facebook.com/profile.php?id=$1
fb://profile/(.*)
http://twitter.com/$1
twitter:///user[?]screen_name=(.+)
http://twitter.com/share?text=$1
twitter:///post[?]message=(.+)
...

Do you have a Facebook account setup in System Preferences -> Mail, Contacts & Calendars?