MapReduce is often programmed using Java. However, other options are available. Hadoop Streaming is a utility that is used to program against MapReduce using languages such as C, Perl, Python, C++, and Bash. For example, Python can be used for the Mapper, and AWK for the Reduce.
Hive can be used to program MapReduce using a subset of SQL.
Pig is another high level procedural language created specifically to do MapReduce programming.