I've tried it on variety of different servers/hardware using both my server+apachebench and netperf as benchmarking tools.

* On EC2 I've tried the c1.xlarge and the giant cc1.4xlarge. With cc1.4xlarge, I saw maybe a ~10% increase accept() rate. * Two separate, virtualized servers at the office. * A private, virtualized server on Rackspace was briefly tested as well.

A compilation of netperf results are available at https://gist.github.com/985475