The folks from Alinan have developed a very comprehensive and detailed TCO/ROI comparison tool for the Microsoft Windows Azure Platform. You can access the tool at http://www.microsoft.com/windowsazure/tco/.
This tool does an excellent job of calculating the TCO/ROI of hosting an existing application on the Windows Azure Platform as compared to running the application on-premise. In doing this it considers not only the cost of operation but the entire application life-cycle. This includes planning, acquisition, setup and installation, management and support, evolution and retirement of the application. In the case of an existing on-premise application it also considers the cost of migrating the application.
One impediment to the use of the tool could be that it does require you to know what your existing on-premise application is actually costing you. (Believe it or not some companies do not actually know that!) But never fear. The tool is loaded with lots of industry standard data for all aspects of an on-premise application environment. (The folks from Alinan are experts in this area.) I do recommend that you sit down with your local Microsoft representative to determine the appropriate numbers to feed into the tool.
Here are some screen shots from the tool to whet your appetite . You will be hearing a lot more about it in the coming weeks and months. I will also update this post as more information becomes avialble