Pretty impressive milestone right at the end of the year. You can catch the release notes here. The biggest piece of new functionality may be webhdfs, a complete REST based implementation for accessing HDFS over HTTP. You can use common tools like curl/wget to access HDFS as well as supports all HDFS user operations including reading files, writing to files, making directories, changing permissions, and renaming. Previously people could use hftp from Yahoo! for accessing HDFS over HTTP, but hftp was a read-only and did not provide write access.

To get started, you can browse the webHDFS REST API documentation from Apache here.