The $500 cost does make it impractical for many hobiest -- unless they've seen it demonstrated and then the see it really is a bargin! For anyone for whom modelling time is money SketchUp's price is very easy to justify.

It is the fastest growing 3d modeling program out there and part of the reason is it works quite well with other modelling programs. @Last, the developers of SketchUp, don't aim to have existing 3d users switch from their programs over to SketchUp. Instead, they are trying to have them discover how SketchUp can work with their programs to created a more productive workflow. Word is getting out. It is getting used by some game development companies for game level planning.

One of the more interesting uses is for the Hollywood types. Apparently even Steven Spielberg has used SketchUp. It is useful in storyboarding and in planning productions. The tv series 24 with Kiefer Sutherland uses sketchup to plan every shot. Much of that series is shot with just two cameras and through modelling they can accurately plan all the shots efficiently. Looking through the SketchUp camera they can know ahead of time just what they'll see. It speeds up production and reduces costs.

Regards, Ross