ScreenFlow is my favourite screencasting software tool and the one that I use to make all the video tutorials for my Tech Tools for Teachers series on OneStopEnglish and for the award winning Blended Learning in ELT course I designed for Bell. I'm now using it to create iPad tutorials and it works really well.
~Record from desktop, a video camera, microphone and computer's audio all at the same time
~Full screen HD capture, optimized for the best, most efficient screen capture
~Intuitive editing interface allows you to add professional touches
~Keynote and PowerPoint support
~Full range of elegant 2D & 3D transitions
~Publish directly to YouTube, Vimeo or Flash movie
~Optimized to take advantage of productivity enhancements in Mac OS X Lion