"As I blogged last week, Microsoft is seeking ways to boost sales of its Azure platform. One way the company is hoping to do this is by tightening up its developer story around Azure."
While Azure was largely blamed for Ray Ozzie's departure (http://itknowledgeexchange.techtarget.com/IT-watch-blog/ray-...)
You can look at the anemic selection of Azure Books: http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dap...
(By comparison look at WPF books a technology most people believe will disappear into Silverlight in coming years: http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dap...)
I'd also point to the number of views on the average Azure article on DotNetKicks: http://dotnetkicks.com/azure
But to be honest I mostly based it on my own experience. I know many .Net developers and all of them have chosen to ignore the benefits of Azure and go with the more difficult task of implementing on EC2.
Note I'm not saying Azure isn't a good choice. I'd even argue it's a better choice in many ways than services like EC2 (Scaling alone makes it worthwhile for .Net developers). I'm simply saying it hasn't been a success for Microsoft thus far.