Die Seite von den Autoren (Diplomanden) des Buches http://www.amazon.de/E-Learning-2-0-Einsatz-Nutzer-WikiBlog-Caster/dp/3940317160/ref=sr_1_2?ie=UTF8&s=gateway&qid=1201107646&sr=8-2
"A tumblelog (or tlog) is a variation of a blog that favors short-form, mixed-media posts over the longer editorial posts frequently associated with blogging. Common post formats found on tumblelogs include links, photos, quotes, dialogues, and video."