Check out 3D World magazine, June & July 2009. There is a great Kyle Balda masterclass on animating a 2 person dialogue shot, that has been passed around the labs quite a bit lately.
June Issue videos and July Issue videos
The magazine lecture notes are really concise and very insightful, especially for students experimenting with 3D work flow and looking for a clean way to layer in and build up animation.
The magazine is worth the purchase since it gives you the lecture notes and a CD with the Maya files containing the 2 characters, as well as individual Maya files showing you Kyle's separate animation passes. You can go right into the graph editor and see exactly what he did in his passes. What great learning material!