You can start developing Office and SharePoint apps with Windows Azure integration easily.
With your Office 365 Developer Site, you get an isolated app domain for SharePoint-hosted apps, preconfigured to use OAuth, so that you can use the Windows Azure Access Control Service (ACS) for authenticating and authorizing  provider-hosted apps for SharePoint that are deployed to this site.
Now, you have a test environment for starting development for Microsoft Office 3s65 with Windows Azure.
It's good for developing productivity applications that'll work with Office 365.