Well, I don't think it's backwards compatible - so If i make a plugin with the 3dsmax 2010 sdk - then you cannot use 2009 version of max with this plugin. (This is where maxscript is very good, compatible as long as you do not use newer functions not in older release).
Of you need to get older SDK's also and compile with them too.
But I think having for max 2010 now, and then next step is to compile for 2011 version, and then later on compile for both would be fine.
Maybe when development picks up speed we can have some user polls to see what versions of max everyone uses etc. And how we should support it.
Do you have some kind of status for your scripts? what works now? Do you need\want help with the maxscripts?
Well, everything works. I can easily create images with it. Check the posts in core dev/gpu. I posted some nice image like this.. Basically bug hunting and some simplification I do these days. Right now I unify the texture export. It will automatically render not PNG images into PNG file format into an other location, and it does with procedurals as well.
A little scary to have so many kind of sdk. I might just stick to maxscript even if it is slow. Geometry basically have to be exported only once. If one follows the general way of building the scene. Of course adding uvw maps, could change it. Maybe in the future I add the option to replace individual objects, so that it would be able to maintain workable speeds at geometry export.