Looks like there might be a new definitive answer to screencasts:

ScreenFlow, from Vara Software

A bit expensive compared to iShowU or even Snapz Pro X, but given that it’s an all-in-one package that has some majorly cool features like after-the-fact mouse and keystroke highlighting (!!!), it could well be worth the investment for anyone making screencasts much. I’m definitely going to download and try it out, that’s for sure. Leopard only, unfortunately for those running 10.4.