Just when you would think that Google forgot about further developing SketchUp, they release a new update. Version 8 boasts some improvements (welcomed), but nothing as revolutionary as in the early days, when e.g. "slices" were introduced.
- [Pro Only] "real" solid operations are nice. There was already the "intersect" option, but that left the cleanup work still to be done. Now you can do a proper Boolean union, subtract and intersect and also a trim and split option is available.
- [Pro Only] Layout has been improved with better dimensioning, more accurate moving operations and better control over linestyles such as dashed lines.
- Better geo-location options, using Google Maps. Now you can do all the work inside SketchUp, which is really nice (and a good thing for Google). You choose a section of a map and directly load it into SketchUp. You get a more accurate result than before and the terrain model you get is now also in color (it used to be in greyscale only).
- Photo Match is improved, to make it a bit easier. Can't comment on accuracy, but understand that proper use of photomatching requires some insight into the model and some geometrical logical reasoning, that not everybody masters.
- Better integration with Building Maker. This is an online tool (integrated with the 3D Warehouse) to create models from aerial photographs. It requires Google Earth plugin to be installed. You get a few pictures, add primitive shapes and position them with the pictures and the photos will be glued on. Now you can open and refine the models from Building Maker.
- Outer shell, to shrinkwrap a volume with a closed shell. This should be very interesting for Rapid Prototyping, when you need to export closed, watertight STL models.
- [Pro Only] DWG/DXF 2010 support.
- And some other improvements.
In summary, geo-location improvements, real solid operations, Outer Shell and better DWG/DXF support are the highlights and thus using the Pro version becomes more important for Architects and engineers. According to the movie below, solids, geo-location and layout are the three major highlights ;)
That said, even if SketchUp would still work as it did in release 2 or 3 it would still be an essential application for architects.