On his Web 2.0 Teaching blog, Alan A. Lew points out a new mashup tool from Slideshare: Slidecasting. A Slidecast synchronizes an uploaded PowerPoint presentation with an MP3 audio file (that must live somewhere else on the web). Slidecasts do not incorporate video of the presenter—compare with Zentation, a web-based mashup that does include presenter video—but Slideshare's embeddable results look very slick.

Sites like SlideShare and Zoho Show are making it easy to post and share PowerPoint presentations via the Web. YouTube and Google Video, meanwhile, offer venues for video sharing. Now Zentation