Google has finally realized that it's a bad idea to automatically add to the list of Gmail contacts all the people you've sent an email. An updated version of Gmail's contact manager has a separate section for the people you've emailed: "suggested contacts".
"My Contacts is a place to import, store and view all of the contact information that's important to you. You can also create your own groups of contacts to easily email many people at once. We add people you've emailed to Suggested Contacts. You can move contacts from Suggested Contacts into My Contacts at any time."
There's an option to automatically move suggested contacts into My Contacts if you frequently email them, but the previous behavior doesn't seem to be an option.
I don't have this version of Gmail Contacts yet but when I do I'll look at making that my permanent home for contacts. (Which would be a nice plus, given that I use Gmail for mail and Google Calendar for scheduling.)