I thought I should do something about the jabber:iq:gateway protocol that has been around for so long, but got very disappointed.
The jabber:iq:gateway protocol is now found in XEP-0100 (http://www.xmpp.org/extensions/xep-0100.html#addressing-iqgateway) and is being used in three cases, getting a prompt and description for a certain gateway, and using the native user ID (ICQ screen number etc.) to get the full addressable JID. Doing tests on a number of gateways I was disappointed to see that essentially only the description was returned. The very useful feature to get the full JID when sending a nonempty prompt (native ID) didn't work for any of them.
Instead I did all preparations necessary to activate this code when gateways start to work in this respect. At least I switched on the prompt of the gateway returns a nonempty one. The ones I have seen return an empty prompt element which seems pretty useless.