Though one would think the $field object is what we wanted-- the actual object we needed is $row (even though we're only looking at one field in the row).
Put the following into the field tpl file to see what the necessary info is:
<?phpprint '<pre>';print_r($row);print '</pre>';?>
Then, to actually make the link, put the following in your field tpl file:
<?php$account = user_load($row->uid);print l($row->profile_values_profile_fullname_value, 'users/' . $account->name);?>
Change 'profile_values_profile_fullname_value' to the proper field alias (based on the $row output). Also, be sure to change 'users' to whatever the path is for your user accounts.
I also had another thought-- given your use case, you may want to consider the http://drupal.org/project/realname module as well. It will replace usernames with whatever field(s) you designate all over the site.
EDIT: I had another thought. I'm not sure of the performance implications of doing a user_load in the template file. Another option is to add the 'User: name' field to the view but exclude it from display. Then you could avoid the user_load and change the code in the tpl file to:
<?phpprint l($row->profile_values_profile_fullname_value, 'users/' . $row->users_name);?>
