Disable admin notifications

gistfile1.xml

<!-- in local.xml -->

<!-- Note that enterprise modules have dependencies to Mage_AdminNotification, so disabling it this way could break something -->
<config>
    <modules>
        <Mage_AdminNotification>
            <active>false</active>
        </Mage_AdminNotification>
    </modules>
</config>

<!-- or: in layout xml -->

<config>
    <adminhtml>
        <events>
            <controller_action_predispatch>
                <observers>
                    <adminnotification>
                        <type>disabled</type>
                    </adminnotification>
                </observers>
            </controller_action_predispatch>
        </events>
    </adminhtml>
</config>