As a second source (it's sometimes helpful to hear material from more than one perspective), UC Berkeley has some podcasts from a Scheme course which uses SICP:

http://webcast.berkeley.edu/course_details.php?seriesid=1906978270

I listened to a few of them a while back, just to check them out. Not bad, if you can ignore the lecturer's occasional side-trip into politics (well, it IS Berkeley).