There are many changes to the VSTA framework:

1. Revit VSTA no longer depends on the proxy DLL. Macros are now written referencing RevitAPI.dll and RevitAPIUI.dll directly. This allows macros access to the full features of the Revit API, including generic methods, all events and other methods missing from the proxy previously.  Module templates have been updated accordingly, and the references will be added automatically when upgrading macros from previous releases.
2. The entry point classes ThisApplication and ThisDocument have been adjusted to the direct reference of the API classes.  They also now represent UIApplication and UIDocument (instead of Application and Document).
3. The Transaction and Regeneration attributes must be applied to the ThisApplication and ThisDocument class. Their meanings for VSTA are same as for external commands.  Module templates have been updated with default assignments, but upgraded modules must have these added manually.

• A special AddInId attribute can be added to modules.  This allows VSTA macros to work with updaters.  When new modules are created this attributes is automatically generated with a random Guid.
• The Module_Startup methods are now executed at the time when the module is first loaded (as the Revit application starts for Application-level macros, and as the document is loaded for document-level macros).

4. No transactions may be opended in the Module_Startup and Module_Shutdown methods.

New modules created in Revit 2011 should be “ready to code” – all framework changes have been incorporated into the templates.

Upgraded macros and modules will need to be adjusted to the framework changes mentioned above, as well as all of the API changes (namespace changes, modified APIs).