Autodesk has announced today a new Software Developers Kit "SDK" named Autodesk RealDWG 2006. This is a product for C++ and .NET developers to incorporate 100% DWG and DXF drawing files into their host applications. Host applications writing DWG files with the Autodesk RealDWG will be writing the same DWG file format as Autodesk AutoCAD does without requiring AutoCAD be installed on the same computer. The Autodesk RealDWG can read DWG files from AutoCAD 2.5 and write 100% DWG files the same as AutoCAD 2000 up to the current AutoCAD 2006.
Some current Autodesk non-AutoCAD based product use this same technology today like Autodesk Inventor, Autodesk 3ds Max, Autodesk Revit, and Autodesk Viz. There are also currrent 3rd party applications using the same technology formally known known as ObjectDBX and used by applications such as Navisworks.
For more information on Autodesk RealDWG 2006
Autodesk press release
Autodesk Introduces Software for Developers to Create High-Quality, Cost-Effective Applications
Don't settle for anything less than 100% Autodesk RealDWG.