Mike Arrington just blogged about tomorrow's launch of Slidecasting by SlideShare. Slidecasting is a new media format, the combination of Powerpoint slides (everyone has the authoring tool) and audio (can be located anywhere), including podcasts (where it gets interesting). While I'm a biased advisor to SlideShare, you will have to agree that multimedia on the web just got a whole lot easier and accessible. And as objects you can socialize.
Here's an an example:
If I was an event organizer or podcaster, I'd be setting up a group on SlideShare now.
UPDATE: Launched, see the FAQ
UPDATE: Made my first Slidecast. All it took was the time to listen to my 13 minute presentation while sliding some markers. The editor UI is really easy.
