http://area.autodesk.com/blogs/ken/3ds_ ... _announced
However, there's also this sweet tidbit:
It's always something, I guess. Fortunately, I suspect there can't be a whole lot of changes to the code of a 2012-capable plugin. Hopefully just a re-compile against the new SDK infrastructure? Maybe not.Plug-in Compatibility
Unfortunately, you can’t use 2012 plug-ins with 3ds Max 2013. The SDK is different from prior releases due to the move to Unicode (finally) in this release. This is an example of a massive sw engineering project we had to undertake to deal with legacy code. This was by far, the largest investment in touching all the code in 3ds Max since 64b. Unfortunately, most of you don’t care that we’re now Unicode, but it will make life a lot easier for everyone working with 3ds Max on a foreign OS or are using one of the 5 language versions 3ds Max comes in and are trying to share data. Don't forget, you still have a "save as 2010" feature in this release to maintain data compatibility with older pipelines.
In the meantime, one would need to use this "save as 2010" feature to maintain compatability, seemingly.