Virtual infrastructure v Terminal servers
Virtual infrastructure based on products like Microsoft Virtual Server, VMWare and Xen is the flavour of the month. People are talking about reduced cost of ownership, energy consumption and increased security risks resulting from use of virtualisation - all of which is questionable. But without a doubt virtual infrastructure, especially in the datacenter space, will change the way we do things today. System deployments will take much less time. Recovery procedures will change dramatically. In enterprise space, virtualisation will change networking and storage architecture as well: IP subnets will span multiple physical sites, and storage will become more flexible. I'm doing my reading on iSCSI - IP-connected storage is the way to go.
There are other effects of the emergence of vitualisation. Blade servers won't ever become mainstream solution because of it, and possibly will die off altogether. And there will be a very interesting clash with terminal server solutions - technology space dominated by Citrix Systems, History of terminal servers is interesting: developed as a way of enabling multiuser access to systems, it evolved into bandwidth-saving way of using legacy applications, then to the core of thin client infrastructure (remember Oracle's Network Computer?) and now it's all of the above plus secure remote access mechanism and software distribution application delivery system. Virtual infrastructure hosting any modern OS has all the same features - but approach is different. Some may argue that terminal servers are utilising less resources since htey are using single OS image for all clients - which is probablu true, but becomes less of an advantage as both VM resource management ans sytems' awareness of the virtual infrastructure improves. And terminal servers can become legacy systems themselves.