Today I was pointed to my previous post on scaling, and I remembered, that I didn’t put my slides from MySQL Users conference online. Maybe those are not giving that much of detail, but still, can disclose some of facts from my talk: “Wikipedia: cheap and explosive scaling with LAMP”.
There’s also Brion‘s presentation at Google on wider aspects of project technology, with slides and video made public too.
domas mituzas 
The best way to optimize a request – kill it :)