Heh, I forgot we now have a machine in our office with Leopard installed, so this AM I sat down for 20 minutes with ScreenFlow. It's pretty nice, and the editing features are really slick. Very nice callouts and zooms and mirror effects. But no text can be added, which is a really big bummer. Nor arrows. And I'm sure you can add additional clips to compensate, but I didn't see any way to add a title screen during my inaugural run. It was stable for me on one try though. I only saw variants of .mov files as the output, but you can upload those to YouTube or Viddler for conversion. More when I have more time, including some sample screencasts.
Technorati Tags: ScreenFlow, OSX, Screencasting