A while ago I was complaining on list that I couldn't find a decent comparasion between Apple hardware running Linux and an x86 machine.
Another thing I was interested in was the comparative performance of running services such as apache or mysql.
Anybody else interested should read this http://www.anandtech.com/mac/showdoc.aspx?i=2436 (use the "Print this article" at the bottom to get it on one long page)