It’s great to see that the RTM version of the Visualization and Modeling SDK is also available at the launch and release of Visual Studio 2010. For details check out http://code.msdn.microsoft.com/vsvmsdk. See also Jean-Marc’s announcement of this.
As well as the DSL Tools which has been much improved in this release (see What’s new), it also includes some project templates to get you started with extending the UML Tools in Visual Studio. Enjoy.