Scott Hanselman does a demo of the preview tab and solution explorer at DevReach 2011: https://www.youtube.com/watch?feature=youtu.be&v=KVbsNgN4wJg&gl=GB
Start watching around 27:21 if you want to jump quickly to the preview tab and solution explorer stuff. It's an entertaining and incredibly informative talk all the way from start to end though so you might want to watch all of it.
I work on the user experience design for the preview tab and solution explorer and would really love to hear your feedback about this experience.
You can even play around with this yourself. Go to http://www.microsoft.com/download/en/details.aspx?id=27543 to download and install the Visual Studio 11 Developer Preview. You'll then be able to use the preview tab and new solution explorer.
There are some more details about the prevew tab in this post: http://blogs.msdn.com/b/visualstudio/archive/2011/10/07/improving-developer-productivity-with-visual-studio-11-developer-preview.aspx