Ken - I've been using SketchUp for presentation to clients since V4, importing AutoCAD solids and doing JPGs and then animations. The section tools offer very powerful ways to show how the building fits together.
I currently use HSB / AutoCAD for most timber work (sales models, estimating, design, limited shop drawings, etc) - and while the tools are powerful they come at a steep price tag and learning curve. SketchUp, being free or pro for $500 eliminates 1 of those obstacles. The learning curve is pretty shallow too - esp for 'boxy' objects like timbers.
I have not found a more pleasant or friendly way to share data with clients, architects, and even sometimes engineers in the visualization phase of a project (and even later on - when we get into SKs for how things might be fit together under unforeseen circumstances). If folks do not want to download SketchUp or have fears of operating it - the slide show animation can be exported to a video, posted to the web, burned to CD, or emailed - allowing the sense of motion and seeing how various pieces fit together. Most clients can open a model and click through the tabs...
Intellectual property is a bit of a problem - not just with SketchUp but with electronic media in general. If we were on an HSB forum I doubt I would have posted a full model. With two of the large companies I was formerly employed (and now continue to do much freelance work) I've collaboratively invested time and $$ working to develop custom joinery solutions that transfer to CNC and streamline the shop drawing process. These items make the firm far more competitive in the market - something that has been discussed by all parties involved in developing the tools.
In a way SketchUp has opened sales doors for me as I can present in a way most timber framers (and companies) cannot. I'm open to investing in and sharing these tools and techniques though because I see this as more of a 'framing square and chisel' style of tool compared to a fancy graphics package and investment in a CNC machine. The hope is that by the time everyone makes a digital presentation of a prospective frame standard procedure... I'll be out front with something else...
I've been searching around for ways to 'lock' or watermark a 3d drawing. Not really finding any solid solutions yet.
-Mike