Still in use (though not by the military) until fairly recently. Without considering RFC 1149 (and the updated RFC 2549), despite the efforts of the Norwegian BSD (and) Linux group[1], someone in Africa has used pigeons to demonstrate that the telecoms service was nowhere near fast enough[2].
(With the current rise in government snooping I wonder if the humble pigeon might make a comeback.)
Chris.
[1]
http://www.blug.linux.no/rfc1149/
[2]
http://news.bbc.co.uk/1/hi/world/africa/8248056.stm