Is there comparable functionality of Word.Document.WordOpenXml in Excel & PowerPoint?

Question

In the Word Object Model (version 12) there is a property called WordOpenXml on the Document object which returns a flat XML format representing the Open XML for the document. Details can be found at: http://msdn.microsoft.com/en-us/library/bb242889.aspx

Is there similar functionality to be found in the PowerPoint Object Model and the Excel Object Model? I've searched through the two Object Models and don't see anything.