VS2010 and VS2008 project compatibility

Question

Does anyone know if VS2010 will use the same project & solution file format as 2008, or will the 2008 project files need to be upgraded to 2010 format before they'll open in that version?

Answer 1

"Visual Studio 2010 will allow you to move your projects from previous versions of Visual Studios to VS 2010 with ease, I will call this process as “Converting” the project from VS 200X to VS 2010…

VS 2010 will also allow you to change your project’s Target Framework Version to .NET 4.0 from .NET 2.0, 3.0 or 3.5… I will call this process as “Upgrading”…"

extracted from http://vishaljoshi.blogspot.com/2009/05/vs-2010-project-conversion-upgrade.html