Just got back from the Usenix/Lisa 12 conference in San Diego, and had a great time, super inspiring talks and content.
Highlight of the conference for me was Brendan Gregg speaking on Performance Analysis Methodologies - most of his talk was based upon a paper he just published in ACM - Thinking Methodically About Performance.
The talks haven't yet been published on the Usenix website, but Brendan's blog has a ton of great looking content and older talks including this one on Visualisations for Performance Analysis