Have you ever tried to create and modify 3D objects in AutoCAD? Prior to release 2007, that was not an easy task and generaly, "serious"3D was done in softwares like Max, VIZ, Rhino...
AutoCAD 2007 brings a revolution to the way we do 3D in AutoCAD, now you can loft, sweep, modify 3D solids in real time, this is the biggest new functionnality in this version and the rendering module has been updated too.
Appart from that? Well, let's say, nothing much... OK, you can overlay DWF files in your DWG, you can publish PDF directly from AutoCAD, but the big thing is 3D.
See this video for creating a loft object.Have a look at the photos galery for screen captures.