Klaus posted an article about this subject in his blog recently. In summary, Corel DESIGNER Technical Suite X4 will come with support for AutoCAD 3D DWG and DXF, 3DS, VRML, U3D, SketchUp files and a few other file formats. There will be an add-on package to DESIGNER that will include support for CATIA®, Inventor®, Pro/ENGINEER®, SolidWorks®, and Unigraphics® NX, and 3D exchange formats such as IGES, STEP, SAT (to name a few). The add-on is actually included with the pre-release version. More details will be available with the official availability announcement of DESIGNER X4.
Gérard