I recently received a note in Mail with updated info from one of my contacts. As I moused over it, gray dashed lines appeared around the address, email and phone info, along with a small white triangle in a gray box. Right clicking produced a menu of options, as pictured.
Clicking “˜Add to Existing Contact”¦’ brought up a window showing the Address Book entry for the contact, with the new info neatly replacing the old. Clicking “˜Add to Address Book’ updated the entry. Very cool”¦