On Ubuntu 11.04, adding ‘gcin’ into array variable after checking its original value.
$ gsettings get com.canonical.Unity.Panel systray-whitelist
[‘JavaEmbeddedFrame’, ‘Mumble’, ‘Wine’, ‘Skype’, ‘hp-systray’, ‘scp-dbus-service’]
$ gsettings set com.canonical.Unity.Panel systray-whitelist “[‘JavaEmbeddedFrame’, ‘Mumble’, ‘Wine’, ‘Skype’, ‘hp-systray’, ‘scp-dbus-service’, ‘gcin‘]”