Well, I noticed recently that google Meta description differs.

Google
Search engine returns keyword search results based on relevance of content and the number of links to a particular URL from other sites.
www.google.com

Google
Develops Internet search technology.
www.google.com

Google
Enables users to search the Web, Usenet, and images. Features include PageRank, caching and translation of results, and an option to find similar pages.
www.google.com
  

Try it on MSN Yahoo Altavista or GOOGLE and you will find some different description.

Not all of them within the www.google.com domain has been targeted JUST for the internet users (mass audience)

Can some find out more, and what is the purpose ?
(Elias Canetti reffering to MASSE et Puissance)

with Google Power, they might be able to deliver a mass message easily.

I suppose those descriptions are delivered via the Open Directory Project at http://dmoz.org