If you're on PC, you have it now. This is what the reference guide says about it:
3D Content in PDF (WIN only)
When creating a PDF, ArchiCAD allows you to take advantage of the U3D file format (in Windows only).
When publishing a PDF document from ArchiCAD, you can embed a U3D file into the PDF, then “navigate” the view within the PDF as if it were a 3D model.
1) From the 3D window, save the desired model view as a file using the “Save as” command. Choose the “U3D file” format from the list of available formats. It is recommended to clear unnecessary detail from the 3D model as much as possible, in order to optimize the navigation speed in the resulting PDF document.
2) In the Navigator or Organizer Palette, save the desired model as a 3D view. If you prefer, add the 3D view to a Layout.
3) Next, add the 3D view (either on its own or as part of a Layout) to a Publisher set. Select the 3D view (or Layout) in the Publisher Set.
4) Set the Publisher Set Properties to PDF format. (This is the default publishing format.)
5) In the Format tab page at the bottom of the Publisher palette, choose Document Options, then PDF Options.
6) Check the “Embed 3D content” checkbox.
7) Click the “Browse” button to select the file you saved in U3D format (in Step 1 above).
8 ) If you are publishing a Layout, select the 3D view on the layout into which you want to embed the U3D file. (If you are publishing a view, the U3D will be embedded into that view.)
9) Click OK.
10) In the Publisher, select the desired publisher item and publish it in PDF format.
The resulting PDF file will contain an embedded, navigable U3D file.
The U3D model embedded in the PDF can be navigated only by using Adobe Reader 7.0.
It's quite the process, and in reality, it's only useful for very small models, 3D details, etc.
Cheers,
Link.