Edutopia magazine, published by the George Lucas Education Foundation, publishes  several articles  about education in general as well as articles about the role of technology in education. This article, titled Voice Threads: Extending The Classroom With Multimedia Interactive Albums, gives an excellent overview. Participants in the Muskegon ISD’s Tech Integration Series have been (or will be) trained on this cool resource, but if you want to learn on your own, there are some excellent tutorials on the VoiceThreads web site. It also points out (in the third paragraph and at the end of the article) that there is now a web site where you can find VoiceThreads specific to K12 education.