I noticed that the TableInputFormat lets people set many other options to narrow the range of rowKeys or columns:
http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/mapreduce/TableInputFormat.html

It might be cool to add notes for a few popular options, even if these aren't used in the example. It might not be obvious to people that these options are also configured by setting a conf value with a TableInputFormat key. E.g.:

// Other options:
// conf.set(TableInputFormat.ROW_START, "yourStartKey") 
// conf.set(TableInputFormat.ROW_END, "yourEndKey")