In working with the beta of Adobe's updated Acrobat 9 Pro Extended (nee Acobat 3D) I found that it can import many kinds of supported files -- even though it doesn't look like it can. Here's how:
1. From the File menu, choose Open.
2. In the "Files of Type" droplist, the only file types available are PDF and All Files. Choose All Files.
3. Navigate to a folder that holds CAD files, such as STEP, PRT, or DWG. Select one and click Open.
Acrobat converts and opens the file. Using this method, I was able to view the Pro/E files provided by Via's Open Notebook initiative.
(Warning: IGES files take a long time to open, and can bog down the system.)