iMovie is the free video editing software that comes with all new Apple computers. If you have an older version of iMovie you'll need to pay to upgrade to iMovie 11. iMovie 11 is an intuitive program that lets new and experienced video editors watch video clips, edit video and audio, and share videos on the web or on DVD. With iMovie 11 you can edit HD video, but unfortunately Apple doesn't allow you to burn Blu-Ray DVDs.
Corel VideoStudio is an affordable PC-based editing program that provides user-friendly editing, as well as a wide variety of titles, transitions and templates. Corel VideoStudio includes a wide variety of export options, as well as DVD and Blu-Ray authoring tools.
Pinnacle offers a line of video edting software - from the free Pinnacle Spin to the top-of-the-line Pinnacle Studio Ultimate Collection. All of these let you edit and export HD movies.
Sony Vegas video editing software comes in several PC-compatible version, all of which support HD video editing. And all but the most basic, Vegas Movie Studio, include Blu-Ray authoring software.