The 3ds Max 2011 SDK is a binary backwards compatible SDK release. This means that plug-ins compiled using the 3ds Max 2010 SDK, will run in 3ds Max 2011 without requiring recompilation unless they depend on the Open EXR bitmap IO plug-in.
The key things that plug-in developers must note for 3ds Max 2011 are changes to how we recommend cloning objects, the deprecation of HardwareLockID(), and new guidelines for plug-in developers have been created so that plug-ins can operate normally when a user saves a scene out to a previous version of 3ds Max.
The location where mental ray shaders must be installed has changed from 3ds Max 2010 to 2011. This has an impact on plug-ins that install mental ray shaders. The folders have been changed as follows: