I have just been browsing an interesting project on codeplex which will provide PHP developers with a SDK to enable them to easily access the features of Windows Azure. In particular, enabling developers to access Blogs, Tables and Queues. There will also be helper classes for HTTP, AuthN/Z and REST and error management support.
There are currently three milestones, starting in mid-May and being feature complete in August.
The nice aspect of the project is that through REST, the application could be hosted on Windows Azure or hosted elsewhere , and still be able to take advantage of these assets, which is show through the diagram below.