STEP is still a widely used format for interoperability.
My Acad Mech 2007 has a pull down menu entry for inserting a STEP file, but returns a message that the STEPIN command is not recognized. I've tried finding STEPIN everywhere on my system I can imagine.
I did a FULL install of AM2007, because I like having everything available, so it should be there, especially since it has a pull down menu entry.
What's up with THAT????