Maya, to my knowledge doesn't have a STL export option
but there is a program call 'Polytrans' from www.okino.com
which allows the convertion between many of the CAD
formats and should have STL export option (30 day trial)
However, exporting dxf (polys) or iges (nurbs)files to other packages (Rhino,
3D Max, AliasStudio, Solidworks) will allow you to convert the mesh to STL
format.
Gnomadix