In another report from this year's O'Reilly Open Source Convention, Kevin Yank has covered Rasmus Lerdorf's talk - "Getting Rich with PHP 5" - a look at building rich web applications in PHP5.
PHP's creator, Rasmus Lerdorf, gave a surprising talk on building PHP rich web applications using PHP5—suprising, because fully half the talk focused on low-level PHP optimization techniques. The slides are available online.
Kevin gives an overview of the talk, mentioning some of Rasmus' examples, the bottlenecks he defined, and the time spent on the new functionality in the PHP 5 series.