I am new to inventor and would like to know if you can take a autocad 3d drawing and import it to inventor 11 as a 3D drawing.  I have been able to do the 2d drawings.  Is this possible?

Sure, you can - just import the DWG file in the part modeller.

Or you can save it as a .sat in Inventor then in Autocad INSERT>ACIS (.sat)