Hyperthreading degrades performance?

This is in reply to the people who said this because of
cache-contention. Has anyone benchmarked this?

There's an article

http://www.2cpu.com/articles/41_1.html

that benchmarks hyperthreading in Linux and shows a modest (~29%)
improvement in performance --- depending on applications (with java
showing degradation of performance). Perhaps the linux sheduler does
things differently...