Individual organisations maintain their own physical servers and these can be accessed through the TCP/IP protocol.
Currently, on these servers, we run the same HTTP application server (the 'web server') .. and anyone anywhere in the world can connect to the HTTP application server through the HTTP client ( the 'browser')
Similarly, going forward, organisations can run their own SL servers on their own hardware and and allow ( or disallow ) individuals to connect their SL clients .. and this 'visit' SIMs ( just as we visit websites today)
On current HTTP application servers we run fancy stuff like java applets, Flash animations, RealAudio and YouTube style specific applications ... provided they comply with correct protocols and clients must have the required plug-ins
Similarly on our SIMs we can run fancy stuff ( not sure what ?) and as long as they comply with protocols and the SL clients are configured to access them.
One major difference is that browsing on the web is an anonymous exercise ... the server has no way of knowing who am i ... also when i am browsing, artefacts that belong to me ( cookies etc ) remain on the client machine ..
In SL that is different .. we need an identification and also a place to store our assets ...
So there has to be a central identification management agency that will ensure uniqueness of avatarIDs
In certain countries, the SSN could be a source of uniqueness (though revealing that will be a big blow to our privacy ) but that is not universal. So it is likely that there will be a parallel ID system that will be created ( do i see the beginnings of a global SSN ? )
The concept of a central identity management mechanism is an intriguing possibility ... going forward, avatars will have a global ID and they will also need a global "warehouse" where they can store their inventory of artefacts .. and i suppose there will be competition from different agencies to act as the "warehouse" ... just as banks compete with each other to be the custodians of our cash.
Who will run this central identity management service ? would it something central ? or would it something heirarchical like the DNS service ? with a core group of identity servers ? would our avatarIDs become something like prithwis.ibm.sl ( provided by our employers ) and would there be people like Yahoo and Google who will tempt us with (free ?) identities like BigBoss.yahoo.sl or SmartOne.gmail.sl ? and will these link to our current names like Calcutta Cyclone ?
The possibilities are enormous and extremely exciting ...