Autodesk Labs http://labs.autodesk.com/
Scott Sheppard mentioned and detailed this new addition in the blog "It's Alive in the Lab: Technology Preview: Autodesk Inventor 2008 Parasolids and UG-NX Translators Now Available
Technology Preview Added: April 23, 2007
With this technology preview, you can streamline projects that require opening files from vendors or customers in native formats. You can easily exchange data between Autodesk Inventor and UGS by importing and exporting Parasolids parts and assemblies, and importing UG-NXTM parts and assemblies directly with Inventor.
Requirements: Autodesk Inventor 2008
Read the FAQ