Now available via Software Update for QuickTime 7.0 users:
QuickTime 7.0.1 provides several important bug fixes, a security enhancement, and improved compatibility with Final Cut Studio. This update is recommended for all QuickTime 7 users. For detailed information on the security enhancement, please visit this website:
http://www.info.apple.com/kbnum/n61798
Important Notice to QuickTime Pro Users
Installation of QuickTime 7 will disable the QuickTime Pro functionality in prior versions of QuickTime, such as QuickTime 5 or QuickTime 6. If you proceed with this installation, you must purchase a new QuickTime 7 Pro key to regain QuickTime Pro functionality. After installation, visit www.apple.com/quicktime to purchase a QuickTime 7 Pro key.