Ability to set an "other" activity
This would benefit from #4417 (closed): Render emoticons in status and PEP text.
In addition, the specific activity element can be \<other/>
in order to handle activities not defined herein.
In the absence of a \<text/> element, the recipient is free
to draw whatever conclusions he or she may like regarding the
nature of the "other" activity. Naturally, emoticons can be
provided as the XML character data of the \<text/> element. ;-)