As a user, when editing my profile page at user/[uid]/edit, Drupal complains after submit that, "Fatal error: [] operator not supported for string line 678 fb_user.module."

The problem is the conditional only asks if ($edit['map']) {. Change to the following to correct:

<?php
// starting at line 672
/**
 * Implements hook_user_update.
 *
 * User is about to be updated.
 */
function fb_user_user_update(&$edit, $account, $category) {
  if (isset($edit['map'])) {   // <-- add the 'isset()' function to avoid this warning w/ php 5.3
    _fb_user_set_map($account, $edit['map']);
  }
  else {
    // Delete account mapping, because administrator has unchecked the connect option.
    $num_deleted = db_delete('fb_user')
      ->condition('uid', $account->uid)
      ->execute();

    fb_invoke(FB_USER_OP_POST_USER_DISCONNECT, array('account' => $account), NULL, 'fb_user');
  }
}
?>

I am sorry I didn't roll a patch. It's one line, and the project I am working on already has 4 other changes from other issue queues to fb core that I wouldn't want to add to this issue.

Joe