Firstly the communal areas and homes will be designed by the games companies. Any content placed in them looks to be chosen from a fixed selection of content provided by Sony or anyone they do deals with, this makes any database load for items a lot lighter than the load experienced by Second Life.

Secondly it doesnt look like users will be able to run any scripts etc that have a large impact on Lindens servers.

Thirdly looking at the two available videos of Home it would seem that Sony have sensibly decided to make each area of Home seperate, i.e. not visible from other areas this considerably reduces the amount of traffic moving between each server.

This is purely speculation by myself, but i think probably fairly accurate.

Of course, this is sure to be a massive success – so hopefully they have architected it for massive scalability. The uptake curve could be alarming (making SL’s growth look positively pedestrian) and if they’ve not scaled it right we can expect spectacular crashes, lag and all those joyful experiences we see in SL.