Through the Intel ® Cloud Builders program we have been documenting how to build a cloud to address specific usage models. To date, there are 92 of these reference architectures. Getting the cloud software installed is not trivial, maintaining patches is not easy, and migrating to new versions is challenging. On top of this you may well need to install and maintain applications used in the management of infrastructure (example: capacity planning).
There are a collection of applications in the open source community (and more in the traditional software community) that address this challenge.
One example is the Dell Crowbar tool (part of the OpenStack project). Crowbar is a tool to deploy OpenStack and is based on the Opscode Chef product. This is an example of using a sophisticated configuration management tool to radically simplify the setup and initial configuration of OpenStack.
But, tools like Opscode Chef are capable of a great deal more. As an example we are coordinating with Opscode to get the core capabilities we implement in Cloud Builders implemented as a series of Chef recipes and cookbooks to be made available to the larger community.
If you are setting up a cloud, you should look seriously at how you plan to setup and maintain the software that manages the cloud. Tools like Crowbar and Chef can be a powerful way to get started on the right path.