This is a very useful document that brings out the current, common understanding of grids.

In section 3 (page 6), the meaning of the following is not clear, to me: "It is important to note that many Grids today 
are built mostly from non-virtualized IT resources (e.g. computers, storage and networks that are NOT virtualized) and 
yet the virtualization of the application and the information still allows the Grid to create an environment where 
resources can be pooled shared and re-purposed easily."

What is meant by non-virtualized IT resources here and how are the applications and information virtualized in this 
context is not clear. By non-virtualized, which type of virtualization is meant. May be some examples of such grids 
would be in order.