Screencast is the latest entry in the OS X screencast making sweepstakes (joining iShowU and old champ, Snapz Pro X among others). One of the nice things about Screencast is its built-in support for showing keystrokes and mouse clicks, without the need for extra software like Mouseposé. When you type a keyboard command while recording, a bezel will pop up showing what you typed. The specs and price sound good (30fps and less than $30), but it's hard to tell how well it will work for longer screencasts since the demo is limited to 1 minute (and prominently watermarks the video).
Screencast is $29 and the demo is available.