Apache's Hadoop projects is the only available production ready implementation of MapRecudce and it has captured a lot of attention and its popularity is growing fast. No wonder that these two worlds run into flamed and little productive discussions concerning "which one is better?" question.
Well, the interesting news is that two relational database engines are now providing integrated solution of both the worlds:
- Aster - http://www.asterdata.com/product/mapreduce.html
- Greenplum - http://www.greenplum.com/resources/MapReduce/
I am particularly curious how soon will be the Hadoop integrated into Oracle or MySQL database.