// Check for access
      $user      = JFactory::getUser();
      $gid      = $user->get('gid');
      echo "group id is $gid";
      $sql      .= "  AND q.access <= $gid ";

      if ($noauth) {
         $where .= "\n AND a.access <= $gid";
         echo  "\n AND a.access <= $gid";
      }

mysql> select title, access from jos_content where access != 0
    -> ;
+--------------------------------+--------+
| title                          | access |
+--------------------------------+--------+
| What is uncategorised content? | 1      |
| Welcome to Joomla!             | 2      |
+--------------------------------+--------+
2 rows in set (0.00 sec)

mysql>
mysql> select id, gid from jos_users;
+----+-----+
| id | gid |
+----+-----+
| 62 | 25  |
| 63 | 18  |
+----+-----+
2 rows in set (0.00 sec)

mysql>

      $user      = JFactory::getUser();
      $access      = $user->getHighestAccessLevel(); // returns 0 for public, 1 for registered, 2 for special
      $isAdmin   = $user->isAdmin(); // return true if user is admin or admin related ( eg, manager ), otherwise, false

mysql> select * from jos_core_acl_aro_groups;
+----+-----------+---------------------+-----+-----+---------------------+
| id | parent_id | name                | lft | rgt | value               |
+----+-----------+---------------------+-----+-----+---------------------+
| 17 | 0         | ROOT                | 1   | 22  | ROOT                |
| 28 | 17        | USERS               | 2   | 21  | USERS               |
| 29 | 28        | Public Frontend     | 3   | 12  | Public Frontend     |
| 18 | 29        | Registered          | 4   | 11  | Registered          |
| 19 | 18        | Author              | 5   | 10  | Author              |
| 20 | 19        | Editor              | 6   | 9   | Editor              |
| 21 | 20        | Publisher           | 7   | 8   | Publisher           |
| 30 | 28        | Public Backend      | 13  | 20  | Public Backend      |
| 23 | 30        | Manager             | 14  | 19  | Manager             |
| 24 | 23        | Administrator       | 15  | 18  | Administrator       |
| 25 | 24        | Super Administrator | 16  | 17  | Super Administrator |
+----+-----------+---------------------+-----+-----+---------------------+

      $user      = JFactory::getUser();
      $gid      = $user->get('gid');
      echo "gid is $gid<br/>";

gid is 25

if ( ! $user->isAdmin() ) {
  $access = (int) $user->getHighestUserAccessLevel();
  $where[] = " jos_content.access <= $access ";
}

static $lookup;
static $data;

// Initalize if needed
if ( is_null( $data ) {
  // DB code to fetch the table info
  $data = $results;
  $lookup = array();
}

// Check if the ids for this group have been calculated already
if ( ! array_key_exists($group, $lookup) )
  $lookup[$group] = $this->_createGroupIDsForGroup($data, $group);

// Return an array of group ids
return $lookup[$group];

<?php

// J!1.0.12, site
global $my;
echo $my->gid; // '2' for super admin

// J!1.5 nightly, site, legacy mode on
global $my;
echo $my->gid; // '25' for super admin, expected result: '2'

// J!1.0.12, administrator
global $my;
echo $my->gid; // '25' for super admin

// J!1.5 nightly, administrator, legacy mode on
global $my;
echo $my->gid; // '25' for super admin

<?php
// J!1.5 nightly, site, legacy mode on
$user = & JFactory::getUser();
$gid  = $user->get('gid');
echo $gid; // '25' for super admin

// J!1.5 nightly, administrator, legacy mode on
$user = & JFactory::getUser();
$gid  = $user->get('gid');
echo $gid; // '25' for super admin

$user   = JFactory::getUser();
$id      = $user->get('id');
$name   = $user->get('name');
$aid   = $user->get('aid');
$group   = $user->get('gid');
$guest   = $user->get('guest');
echo "User $name ($id) is gid $group and access $aid as a ".($guest ? 'unregistered' : 'registered').' user<br/>';

$user2   = new JUser();
$user2->load(63);
$id      = $user2->get('id');
$name   = $user2->get('name');
$aid   = $user2->get('aid');
$group   = $user2->get('gid');
$guest   = $user2->get('guest');
echo "User2 $name ($id) is gid $group and access $aid as a ".($guest ? 'unregistered' : 'registered').' user<br/>';

User (0) is gid 0 and access 0 as a unregistered user
User2 tcp (63) is gid 19 and access as a registered user

User Administrator (62) is gid 25 and access 2 as a registered user
User2 tcp (63) is gid 19 and access as a registered user

User Administrator (62) is gid 25 and access 2 as a registered user
User2 tcp (63) is gid 19 and access as a registered user

$user1   = JFactory::getUser();
$id      = $user1->get('id');
$name   = $user1->get('name');
$aid   = $user1->get('aid');
$group   = $user1->get('gid');
$guest   = $user1->get('guest');
$admin   = $user1->get('admin');
$type   = $user1->get('usertype');
$message= $guest ? 'Visitor' : ( $admin ? 'Admin' : 'Somebody' );
echo "User1 $name ($id) is $message: gid($group), access($aid), type($type)<br/>";
$user2   = new JUser();
$user2->load(63);
$id      = $user2->get('id');
$name   = $user2->get('name');
$aid   = $user2->get('aid');
$group   = $user2->get('gid');
$guest   = $user2->get('guest');
$admin   = $user2->get('admin');
$type   = $user2->get('usertype');
$message= $guest ? 'Visitor' : ( $admin ? 'Admin' : 'Somebody' );
echo "User2 $name ($id) is $message: gid($group), access($aid), type($type)<br/>";

$user3   = new JUser();
$user3->load(62);
$id      = $user3->get('id');
$name   = $user3->get('name');
$aid   = $user3->get('aid');
$group   = $user3->get('gid');
$guest   = $user3->get('guest');
$admin   = $user3->get('admin');
$type   = $user3->get('usertype');
$message= $guest ? 'Visitor' : ( $admin ? 'Admin' : 'Somebody' );
echo "User3 $name ($id) is $message: gid($group), access($aid), type($type)<br/>";

User1 (0) is Visitor: gid(0), access(0), type(Public Frontend)
User2 tcp (63) is Somebody: gid(19), access(2), type(Author)
User3 Administrator (62) is Admin: gid(25), access(2), type(Super Administrator)

$user = new Juser();
$user->load(#);
$group1 = $user->getGroup();
$group2 = $group1->getParentGroup();
$name = $group2->get('name');