Recently, there was a great scalability milestone for the memcached community. A single-socket T2 server (released over 1.5 years ago) shows World Record numbers with memcached that is traditionally deployed on dual-socket AMD/Intel servers. Full details can be found at:
http://blogs.sun.com/zoran/entry/scaling_memcached_500_000_ops
Additionally, memcached results on Nehalem systems can be found here:
http://blogs.sun.com/shanti/entry/memcached_on_nehalem1http://blogs.sun.com/shanti/entry/multi_instance_memcached_performance