Google recently bought the company that makes SketchUp, the architectural visualization software that is very fast and easy to use. I know a lot of firms that use this including Fitch and HOK.
They mainly bought the company to integrate 3D architectural models with Google Earth but will continue to profit from sales of the professional version. The personal home version is now 100% free and you can use it however you want, including for making models and uploading them for use on Google Earth maps.
A former creative director of mine now works for Fitch and they use this alot in early development of retail designs, fixtures, and interior spaces. Basically they get the whole group into a conference room with a wacom and just start knocking out shapes. Most things in the POP world are flat this works really well.
Architectural firms also like it for the same reason because they can quickly create architectural elements and test out different design ideas.
It might not work that well for ID guys that work on really curvy organic designs, but for those in POP and architecture its a fun tool.
I had a demo copy … liked it a lot but have been too distracted by Pro-Engineer lately to go backto SketchUp… now that its mine for free I think I’ll be using it a bit for some projects that are mainly rectilinear in nature!