It allows you to reuse your Excel or PowerPoint Web Applications in other web pages – such as this blog.

When the original file gets updated, the other location is updated too.  So, I could publish my SharePoint 2010 Overview presentation in SkyDrive, and embed it in a Blog entry called SharePoint Overview.

If the messaging ever changes, or I want to alter it…. all I have to do is update the source and the blog entry is kept up to date.

http://blogs.office.com/b/office_blog/archive/2010/09/23/how-to-embed-a-powerpoint-presentation-on-a-web-page.aspx

Neato.