I've touched on this topic before but it's worth another mention because there's been a recent white paper on the subject. The whitepaper talks about how to deploy SharePoint Server on Windows Azure Virtual Machines. It starts with a clear and concise summary of the cloud offerings as they relate to Azure and then goes into a discussion of reasons why this approach might be suitable. The paper then dives into a step-by-step guide to the actual deployment.
As such, it's a nice balance between the whys and the hows of implementing SharePoint on a cloud infrastructure platform.
The paper can be downloaded here: http://www.microsoft.com/en-us/download/details.aspx?id=34598