A couple of minor issues with Chapter 16 so far (has anyone else actually made it to the end of this book?).
You will have problems when you try to log in as [email protected]. This is because when the account was set up, the password was filtered through the PASSWORD() function, but they do not use it in the select statement for the user login. You will need to either change the administrator password in the database, or reedit all of your code (whether you copied it manually or downloaded it from their site) so that all of your sql uses the PASSWORD() function in the appropriate places.

Also on the edit user page, the code for creating the optgroup is screwed up. Don't know why it doesn't work like it it supposed to, but an easy to fix it is to just rewrite the foreach that generates the optgroup so it looks like this:
foreach ($a_users as $key => $value) {
echo '<optgroup label="' . $value . '">';
user_option_list($db, $key);
echo '</optgroup>';
}
Then your groupings will look like they are supposed to.

That's it for now. I still have about 20 more pages to go in this book, so I will probably be back with more issues, and hopefully some fixes for them.