This tutorial details installation of Varnish on Ubuntu 8.04 (Hardy Heron) and most Debian systems. The following is a description of Varnish taken from the Varnish Project website.
"Varnish is a state-of-the-art, high-performance HTTP accelerator. Varnish is targeted primarily at the FreeBSD 6/7 and Linux 2.6 platforms, and takes full advantage of the virtual memory system and advanced I/O features offered by these operating systems. See Porting for additional information on supported platforms. "
"Varnish is a modern HTTP accelerator offering 10-20 times increased performance compared to competitors, and a major reduction in hardware requirements, especially for online newspapers."
Installation of Varnish on Ubuntu 8.04 is a straightforward installation using apt-get.
sudo apt-get install varnish