Moving to more collaborative web applications

While I was listening to a 90 minute presentation on the Croquet project, I started thinking of what lessons can web portal developers learn from the croquet developers who have no constraints of supporting legacy technology. Croquet, still in early development, uses peer to peer protocols to allow small numbers of users to share a 3D simulation space - 3D graphics, naive physics, IP telephony, etc. are built in.

Users of a web portal do not know who the other users are and can not interact with them. Now, to a limited degree, we could support some interaction between users who have an active session using AJAX: user modifications to a shared data store could be broadcast back out and a Javascript could listen for broadcast changes. However, this requires a central server - Croquet sends changes to an environment (actually, it only broadcasts user inputs and counts on the environment simulation being deterministic - same precision math used on all connected computers, etc.) using peer to peer protocols.