Surprisingly enough, it looks like Hadoop 2.2.0 is supported natively on Windows, which IMO is a great achievement and is a sign of platform getting more mature.
In this article I show how to run a simple WordCount example in Hadoop 2.2.0 under Windows.
First of all, you need to compile hadoop 2.2.0 distribution, which takes a lot of time (and sometimes tweaking pom files). I uploaded a precompiled version here. You need to edit windows environment variables and add path to bin dir and HADOOP_HOME variable pointing to the dir.
Then you need to format node and run example. Following commands do that:
E:\test>hdfs namenode -format
starting yarn daemons
E:\test>hdfs dfs -cat /input/words.txt
E:\test>yarn jar E:\hadoop-2.2.0\share\hadoop\mapreduce\hadoop-mapreduce-examples-2.2.0.jar wordcount /input/words.txt /output
14/06/14 14:29:47 INFO Configuration.deprecation: session.id is deprecated. Instead, use dfs.metrics.session-id
14/06/14 14:29:47 INFO jvm.JvmMetrics: Initializing JVM Metrics with processName=JobTracker, sessionId=
14/06/14 14:29:48 INFO input.FileInputFormat: Total input paths to process : 1
E:\test>hdfs dfs -cat /output/part-r-00000
I hope that Hadoop 2.x gains wide adoption in Enterprise Environment, since the industry needs the next gen standard for distributed apps.