The Chronicle Wired Campus blog had a post yesterday about a cool new feature from Slideshare called Slidecasts that allows you to easily add audio narration to PowerPoint presentations. It sounds like you just upload a PPT to Slideshare, point to an online mp3 file and sync them. This could be a pretty good solution for folks who don't have access to screencasting software like Camtasia to produce narrated presentations.
Jeff Scott has a post on his blog Gather No Dust that details using Slidecast to make a screencast for his library. He posted a comment but I wanted to bring the link up top. Very cool!