As Tobias Schlitt points out in this recent post to the Qafoo blog, the recording of a webinar he did (for Zend) about "Writing Testable Code" has been posted for listening online.

In this session you will gain insight into the secret of writing easily testable code and you'll learn how this relates essentially to good object orientation.

The recording is just one of many webinars Zend offers on a wide range of development topics, including:

• Design Patterns in PHP
• Multibyte string handling in PHP with the mbstring extension
• Strong Cryptography in PHP
• Using Jenkins/Hudson for Continuous Builds

Almost all presentations also come with PDF versions of their slides attached, too.