The author does a great job of promoting Amazon, but never really explains why it is such a magical solution for scaling applications...
One could argue that Google has much more experience with complex applications and huge scale, like Google Docs, Maps or all the Ads stuff and the data mining associated.
One could also say that Microsoft has a long history with developers and will offer the easiest path from the desktop/web to the cloud. Just think of how many companies still use IE 6 because of "legacy" web apps.
Or one could point out how Oracle represents, for many organizations, their data and business logic, even when they don't provide all the business applications. While scalability means savings in investment, business data and processes means clients and revenue.
Or one could talk about IBM and their solid, no nonsense image.
Or VMware, Cisco, HP, etc...
One could say many things, but one should especially say why... this one thinks.