"XEP-0049: Private XML Storage" - http://xmpp.org/extensions/xep-0049.html
Source of Miranda "Jabber notes" plugin - http://code.google.com/p/miranda/source/browse/trunk/miranda/protocols/JabberG/jabber_notes.cpp
Description for Psi+ "Storage Notes" plugin - http://psi-plus.com/wiki/doku.php/plugins#storage_notes_plugin
Source of Psi+ "Storage Notes" plugin - http://psi-dev.googlecode.com/svn/trunk/plugins/generic/storagenotesplugin/
