Hadoop On Azure allows a user to run Hadoop on Microsoft Windows Azure as a service.
As your aware from my previous blog this service is currently in private CTP with limited capacity, and by invitation only.
However my colleague WenMing has added some more capacity today, So if your an academic or researcher doing big data you may attempt to sign up this free service at https://connect.microsoft.com/SQLServer/Survey/Survey.aspx?SurveyID=13697 Please allow one week for us to approve your invitation.
If your interested in what the service is and its capabilities, please take a look at the following learning resources on WindowsAzure.com that Wenming has authored. Wenming would also love to get your feedback on addition content you are interested in for learning about Hadoop.
BigData Hadoop Learning Resources
Wenming has also given talks at Microsoft TechEd discussing the use scenarios for big data and Hadoop. (samples at https://github.com/wenming/BigDataSamples) TEchED: Learn Big Data Application Development on Windows Azure