Below you will find the slides and accompanying sample project that I presented at the January 2008 CocoaHeads meeting in Syracuse, NY. I posted both the Keynote presentation and the PDF export of said presentation. Because it was an informal gathering I decided to use a few of the Keynote transitions that are fun, but maybe a little over the top. If this kind of thing bugs you, rock out the PDF version, it just has the slides.
Also, during the meeting a few folks asked about playing sounds and doing speech synthesis, so you will see simple examples of those technologies used in the sample project as well.
NSNotification and NSNotificationCenter (zipped up Keynote version) NSNotification and NSNotificationCenter (PDF version)