To overclock today, we used Rivatuner, which works well with the Zotac GTX580 AMP! Edition.
Our overclocking experience was fairly positive, achieving another 8.6% on the core clock, peaking at 880mhz. Memory overclocking was limited to around 15%, reaching 1180mhz. This helped the card to render another couple of frames per second in Lost Planet 2 and Metro 2033.