I checked "queue for download" on the errata on the rhn site, then
periodically checked logs to see if stuff happened correctly.  No dice:

Nov 11 09:58:34 tigger rhnsd[685]: command returned: Got unknown action
version 
1 {'version': '1', 'id': 'Action-00009', 'action': "<?xml
version='1.0'?>\012<me
thodCall>\012<methodName>client.update_packages</methodName>\012<params>\012<par
am>\012<value><array><data>\012<value><array><data>\012<value><string>LPRng</str
ing></value>\012<value><string>3.6.24</string></value>\012<value><string>2</stri
ng></value>\012<value><string></string></value>\012</data></array></value>\012</
data></array></value>\012</param>\012</params>\012\012</methodCall>\012"}

Looking in /usr/sbin/rhn_check I see

# action version we understand
ACTION_VERSION = 0
 
There is no errata upgrade for the up2date rpm, and even if there
were we wouldn't be able to auto-upgrade.  Clearly the protocol
version must be decided on via handshake, or via client-side request.
It makes no sense for server-side to decide the protocol version since
that is absolutely guaranteed to cause a client-side failure at some point.