Some cool debug output from presence. Just here for reference.

Navigating to MyWorkSpace
Session is: c5435a5c-ef0e-47f1-806a-78bc8ca6cdba
PresensePortlet.doGet location=~fred-presence Context=~fred
setPresence 07722bae-78cb-43f1-0056-00517927e3bd loc=~fred-presence
getPresentusers ~fred-presence
Navigating to my site
site/1c50bc19-bd71-4480-0003-05a77a41cab2
PresensePortlet.doGet location=1c50bc19-bd71-4480-0003-05a77a41cab2-presence Context=1c50bc19-bd71-4480-0003-05a77a41cab2
setPresence 07722bae-78cb-43f1-0056-00517927e3bd loc=1c50bc19-bd71-4480-0003-05a77a41cab2-presence
getPresentusers 1c50bc19-bd71-4480-0003-05a77a41cab2-presence
In effect the presense portlet is tracking the sessions who have run the presense portlet.
Navigating to Chat
site/1c50bc19-bd71-4480-0003-05a77a41cab2/page/1d49d1bf-b30e-452e-00db-8cd4e7668444
PresensePortlet.doGet location=1c50bc19-bd71-4480-0003-05a77a41cab2-presence Context=1c50bc19-bd71-4480-0003-05a77a41cab2
getPresentusers 1c50bc19-bd71-4480-0003-05a77a41cab2-presence
setPresence 07722bae-78cb-43f1-0056-00517927e3bd loc=72acc769-d887-412b-00ae-d108d3f3dc63
getPresentusers 72acc769-d887-412b-00ae-d108d3f3dc63