So currently we have XEP-0012 which we don't like because of the relative time semantic, it uses. In addition that it is currently used for two different purposes: 1. Discover the time a disconnected user last accessed its account (i.e. was online).
which is solved by http://xmpp.org/rfcs/rfc6121.html#presence-probe-inbound bullet 3 these days. Actually I doubt anything but jabberd1 implements the 0012-way.
