Final Cut Pro 6 > Effects > Video Filters > Video > Smoothcam
Takes 20 minutes of processing per 1 minute of 1080p HD ProRes content on my 3.0ghz Quad-Core/8GB RAM machine.  Once the analysis on a clip is done, you can manipulate the settings to your liking.  The basic idea is that it analyzes the movement and then crops the picture so that it becomes stabilized.  Looks a lot like a Steadicam shot when you're done.  So you'll lose some resolution, but you'll gain a smooth shot.