I have discovered that the new ASP.NET tab in the IIS MMC seems to be broken after you have had a previous version of the framework installed. So this handy tool makes switching versions of the framework for an application just as easy. You don't have to assemble any long command line strings any more. Use it if you have ASP.NET version issues.
Read the complete post at http://www.dotnettipoftheday.com/blog.aspx?id=125