"Microsoft Visual Studio .NET Enterprise Architect includes advanced Visio-based modeling solutions for developers. Based on tools previously found in Microsoft Visio 2000 Enterprise Edition, Visio for Enterprise Architects includes all of the solutions in Visio Professional 2002 plus full-featured database and software modeling solutions."
At first glance I thought that Microsoft was eating into Rational’s lunch, but the later is part of the VSIP (Visual Studio Integration Program), there’s apparently a bunch of things they do on top of what’s provided by Microsoft. Somewhat related: Conceptual Modeling and Markup Languages, Visio-Based Database Modeling in Visual Studio .NET Enterprise Architect (part 2, 3).