Deploying a basic Ruby application in Windows Azure(blogs.msdn.com)
blogs.msdn.com
Deploying a basic Ruby application in Windows Azure
http://blogs.msdn.com/b/tconte/archive/2011/03/24/deploying-ruby-in-windows-azure.aspx
http://blogs.msdn.com/b/tconte/archive/2011/03/24/deploying-ruby-in-windows-azure.aspx
Case in point, running mysql needs a separate web role and costs >$80 where SQL server is $10 (old prices?).
If your building on top of .Net then take advantage of all that native goodness. Otherwise you face an uphill battle in terms of getting it to just work and pricing.
Don't let this ruby carrot fool you...