Apple Computer released an update Wednesday for Final Cut Pro and Cinema Tools. Final Cut Pro 5.0.3 and Cinema Tools 3.0.3 both have brief release notes that simply state that they "provide improved reliability."
The FCP update is 85MB, and can be downloaded through Software Update if you have Final Cut Pro installed, or as a standalone update through Appleis Support site. You can find more information on the update at Appleis Web site.
You can find the Cinema Tools update at the Final Cut Studio update page. Logging in for the update requires your FCP serial number.