To me multimedia storytelling, as it stands today, utilizes both photos, video, audio, and linking technologies. All of these components mesh together with the the intent to give the user a view of a certain topic, even or story. I think the most successful version of current multimedia storytellling is involved with newpaper websites. Particularly the New York Times photo essays and slideshows, such as this one.
Multimedia in the greater sense is anything that combines a photos, text, video, or combination of media. However, today that definition has morphed into a digital sphere, as have many other creative outlets.