They are close, by design. The 3D interchange part of keystone includes
NURBS surfaces, VRML includes WWWInline and WWWAnchor. There are some other
minor differences which we (the Inventor group at SGI) will try to shake out
of the keystone spec (we have a lot more influence over the keystone spec
than we do over the VRML spec).
Sorry, I can't give specifics on which application developers are part of
keystone or estimate when their products will support keystone
(Inventor-subset) in/out. I will say that there are several "big-name"
companies signed up, and that SGI/Silicon Studio is helping make it happen.
All of which is very good news for the VRML effort, since Keystone-to-VRML
and VRML-to-Keystone translators should be almost trivial.