I gave a talk at Devs in the ‘Ditch last week when I was in London. I posted the slides on slideshare: Overcoming Three Pitfalls of Transitioning to Agile.
The very nice people at 7digital made a video and posted it, too. If you can take the time, watch the entire video. Rob Bowyer gave a great talk about kanban and theory of constraints. My part about overcoming these three pitfalls starts at about 42 minutes in.
There are many other pitfalls to transition. This talk had just three of them: the stories are too big, you need experts to do the work, and you implement as layers instead of through the architecture.
I hope you enjoy the presentation and the video.