Both the Improved ArchiCAD connection plugin and the Revit MEP 2013 export plugin can be downloaded here.
"...Interoperability Downloads: This web page contains Add-Ins developed by GRAPHISOFT to achieve improved collaboration between ArchiCAD and other programs from various disciplines.
Improved ArchiCAD Connection Add-In for Revit Applications: Free Add-In developed for use by Autodesk Revit programs in the Structure and MEP disciplines. This application is recommended for use with IFC-based model exchange between GRAPHISOFT ArchiCAD and Revit applications. The Add-In for Revit applications variously enables direct import of ArchiCAD IFC models and IFC model export to ArchiCAD, or serves to optimize Revit’s standard IFC import and export functions used to exchange data with ArchiCAD..."