Today I finished migrating one of my Ubuntu 8.04 Servers from the classic LAMP (Linux Apache Mysql PHP) to L2MP (Linux Lighttpd Mysql PHP). And it ROCKS.
With Apache, my WordPress administration panel took AGES to load. «Lighty» made it blanzingly FAST. I love it. And it was very easy to get the required mod_rewrite rules ported to lighttpd.
Lighttpd is fully recommended.