I'm not sure I'm happy with my statement saying people don't consider it a google invention: clearly map and reduce have been around for a *long* time... But MapReduce really isn't just map and reduce concatenated.
The word "invention" is a bit loaded so I'll sidestep it a little bit. Certainly the concept of map and reduce functions have been around for a long time, but MapReduce is a new framework for processing data sets in a scalable way. It's not just putting map and reduce function together.
Similarly you can argue that Google did not invent link analysis, but that misses the point. Their PageRank algorithm had applied link analysis in a scalable way to a new problem domain (Web) that it certainly stands on its own as a useful invention.
Some developmental psychology researcher even 30 years ago were mentioned the fact that a kind of map and reduce (very similar to MapReduce) decomposition take place naturally while the human mind is thinking. (of course this is a short summary only). Therefore childrens learning to think in a more map-reduce way to solve problems, are getting much more creative.
If this is so, then my conclusion is that we have to expect a huge move forward to the success of MapReduce itself... because it's a natural approach to many problems.
subject: Why MapReduce algorithm is considered a "Google invention"?