NoSQL Movement?

[Avid Fan]

Jonathan Gardner wrote:

> 
> I see it as a sign of maturity with sufficiently scaled software that
> they no longer use an SQL database to manage their data. At some point
> in the project's lifetime, the data is understood well enough that the
> general nature of the SQL database is unnecessary.
> 

I am really struggling to understand this concept.

Is it the normalised table structure that is in question or the query 
language?

Could you give some sort of example of where SQL would not be the way to 
go.   The only things I can think of a simple flat file databases.