I spoke about Developing Plugins For WordPress on Wednesday, 18th June 2008 at the Singapore PHP User Group, June 2008 meetup.
This is the second time I am speaking at the user group. The first time was in December 2007 meetup where I spoke about the same topic WorPress Plugin Development With PHP.
I think this time my pace was slightly better.
Powerpoint Slides and Source Code can be downloaded here.