Sound Cloud is a web 2.0 tool with an easy-to-use iPad/iPod app. It’s designed for musicians, but language teachers should take advantage for in-class voice recording. Students need to create a free account, then make their recording, which can be emailed to the teacher, or posted directly to a Twitter account. Since the sounds are hosted online, you can embed them on a class website or blog.
Actually, this would probably be better for a podcast.