Interactive 3D content finally usable in PDF presentations.
Some time ago Adobe annoounced that they were going to embrace
the new 3D CAD format called U3D, and intergrate it into
products like Acrobat.
Now that the latest version of Acrobat and Acrobat Reader is released
things are finally starting to look very promising for people wanting
to be able to showcase 3D files into their presentations.
Here more information can be found:
The Impact of U3D on Product Lifecycle Management (PLM)
Link
In this whitepaper from Hitachi Consulting the announcement can be found;
"Adobe is pleased to support U3D as a universal format for embedding 3D CAD
data into PDF documents. We are excited about the opportunity that this presents
for companies like Hitachi Consulting to provide new applications and solutions
to downstream users for solving real business problems with a more effective means
to communicate complex and compelling data in the PLM environment.
Our vision is for 3D to become as commonplace as JPEGs are today for communicating
ideas and concepts through U3D and establishing a "new" international language
for business dialogue in an e-document environment."
- Adobe
In the above document you can also find examples of the technique.
Very interesting and inspiring 
Bentley have the following page on their website:
Interactive 3D Within Adobe PDF
Link
Here you find more examples(most of the even animated!)
"Adobe PDF is the ideal format for sharing your AEC drawings and specifications. And now you can create Adobe PDF documents with embedded 3D models. Convey complex 3D designs to all of your partners and clients no matter what tools they use."
"Adobe PDF animations make it the best format for creating walkthroughs and flyovers, developing proposals for review, or communicating construction sequencing."
So, download the new version 7 of Acrobat and check out the coolness yourself
Link
WARNING! People using WindowFX should unload WindowFX before viewing the
3D content since it appear to be the same "sluggish" bugs as when playing
3D games like Unreal 2004 with WindowFX loaded.
Unload WindowFX and the 3D contents should show smoothly