Preview at WWDC likely in June, followed by September launch.
Video of Final Cut Pro X Introduction Now Available
While the videos are not the professionally-produced broadcasts created by Apple for its higher-profile media events, they are of fairly high quality with consistent views of the slides and action on stage and solid audio quality.
Final Cut Pro X is set to launch in June and will be available through the Mac App Store for $299. Information on new versions of the other applications in the Final Cut Studio suite will be released in the future.