On his talks page, Derick Rethans has provided his three presentations for the php|tropics conference:

• Practical Debugging Techniques - Using XDebug to test/debug your app
• Playing It Safe - PHP and encryption techniques
• Clustering PHP and MySQL - techniques for improving your performance through clustering

Be sure to check out all of these talks - there's some great info here (and the Encryption talk provides a really good overview of encryption in general as well as better ways to apply it to your applications).