Zend_Db_Table already allows you to make joins.
Code:
<?php
$table = new Bugs();
$select = $table->select()->setIntegrityCheck(false);
$select->where('bug_status = ?', 'NEW')
->join('accounts', 'accounts.account_id = bugs.reported_by', 'account_name')
->where('accounts.account_name = ?', 'Bob');
$rows = $table->fetchAll($select);