Microsoft’s Scott Guthrie has posted more details of changes in Windows Azure. I was also able to sign up for the preview of Virtual Machines and Web Sites (my web site application is pending).

In the past the Azure portal for managing your cloud services has been functional but ugly and irritating. This has been replaced by a new portal (in preview) which is a great improvement.

Even better, the portal has a REST API which developers can program directly, giving Amazon-like programmatic control of your Azure infrastructure, though I have not looked at the actual API yet. The SDK is open source and hosted on GitHub under an Apace 2 license.

Guthrie talks about scaling in Azure web sites. You can control the number of VM instances used by your web site and “Windows Azure automatically handles load balancing traffic across VM instances”. The one thing I do not see is how you would have instances brought online and taken offline in response to demand. However, given the REST API you would imagine that writing code to do this would not be too challenging. The portal includes a dashboard for monitoring performance so the API can access this information.

You can have up to 10 web sites on a free shared hosting environment, and pay only when you upgrade to a dedicated VM.

Free is free; but once you do scale up it does not look cheap to me. Here are a couple of samples from the calculator:

or for a busier site:

These kinds of figures would put me off moving this site to Azure, for example. That said, I would be interested to see a detailed cost comparison between Azure, Amazon, and other cloud hosting providers like Rackspace.

There are more features mentioned in Guthrie’s post and it does look like an improvement both in features and usability.