Just gone through a new blog post by Jennifer Marsman in msdn blog. It describes how the new Architecture tools within Visual Studio 2010 help you to understand the application you have, design new functionality you need, and validate that your design and your implementation do not deviate. Though I haven't found the 'Architecture' menu item within my VS 2010 Professional Edition RC 2 Trial Version, but then also it is rocking and awesome to have such cool functional block in VS 2010 fully upgraded and registered version!!!
To read Jennifer's Blogpost regarding New Architectural Tool in VS 2010 click here