JanlsFlink,
Imovie was the first version, since then there's been iMovie 2 thru 6 HD. We're waiting on iLife/iMovie 7 to hit the shelves.
http://en.wikipedia.org/wiki/Imovie#Version_history
NEW in iMovie HD 6
Create amazing movies quickly using Apple-designed iMovie themes.
Stunning new real-time effects with no waiting.
Cinematic titling with instant results.
Use new audio enhancement tools such as noise reduction and graphic equalizer.
Switch and share clips among multiple open movie projects.
Easily share movies and video podcasts with iWeb.
http://www.apple.com/ilife/imovie/