There is FreeCad: http://www.freecadweb.org/ And a walkthrough of converting .stl to .stp: http://northernhope.blogspot.com.au/2013/05/stl-to-step-with-freecad.html
Aliens did it They came with their spaceship landing in russia http://www.slate.com/blogs/bad_astronomy/2013/02/15/breaking_huge_meteor_explodes_over_russia.html
Autodesk 2013 stuff and a new UDK Beta on the same day :) Not too much in this release, but Snefer's badass environment is featured on the showcase page.
Quite fancy stuff... good for indies and big companies and their developers. http://blogs.unity3d.com/2013/03/26/unity-and-facebook-are-now-in-a-relationship-and-its-awesome/