Here is the presentation from TechMixer University 2008. The topic is "Getting Started With Ruby" which is designed to teach an introduction of Ruby. Along the way, we will see some interesting Ruby features: dynamic programming, mixins, dependency injection (e.g. how Ruby doesn't require a DI framework). The slide set contains a couple of bonus slides covering Databases, Builder, Hpricot, RSS::Maker.
or view it here on Google Docs