When Windows Azure was first released in 2008 the only programming languages you could use were .NET languages such as Visual Basic and C# and the applications you built had to run in Partial Trust (Similar to ASP.NET Medium Trust).
In the interim we have made a number of changes including allowing applications to run in full trust, native code is now supported (no longer had to be managed code such as C#) and we support FastCGI applications. Which means:
As a result it is now possible to build applications for Windows Azure using languages such as Java, PhP and Ruby. A couple of UK examples have popped up in the last few days.
PhP on Windows Azure
Last Saturday at the Open Space Coding Day on Azure, Martin Beeby and another developer sat down to get PhP running on Azure. It turned out to be surprisingly straightforward to do.
Ruby on Rails on Windows Azure and SQL Azure
Last week Nick Hill in Microsoft UK Consulting Services posted on getting Ruby on Rails running on Azure after a customer engagement.