Azure has offered a Windows-based version of the HDInsight Hadoop implementation since late 2013. Now you have the option of running HDInsight in a Linux implementation on Azure as well.
HDInsight can now be run on an Ubuntu virtual machine, though Microsoft is describing the rollout in typical fashion as a "preview" (which means regular service level agreements don't apply). Right now, it's only an option in four regions, and the Australian ones aren't included -- not surprising, since the Windows version of HDInsight took a while to appear in the local data centres after their launch last year.
One other interesting stat from the announcement: apparently one in five virtual machines running on Azure is Linux. Given the difference in licensing costs between Linux (free) and Windows (not free), we're surprised that ratio isn't actually a little higher.
The first Azure hosted service that runs on Linux [Microsoft Azure Blog]