Activities and the move to context-oriented desktops

This sounds to me like an evolution of session management (which X11 has had in theory and KDE in practice for a long time). Now all that is needed is to rewrite applications to work better with session management, and in particular to start up faster. We currently have a situation in which you can boot to an empty desktop in less than thirty seconds and your applications take several minutes to start. Perhaps the application maintainers can learn something from the efforts of Arjan van de Ven and the kernel people?