Unfortunately when the current version was uploaded the text on the iWare page for the i-model plug-in for Revit was not updated correctly to show 2015 support. This has led to some confusion and questions to support. The page should be corrected shortly.
Just to confirm: The i-model plug-in for Revit works with the 2010-2015 versions of the Revit products, including Architecture, MEP, and Structure, and includes support for the 64-bit versions.