Good advice but I'd argue there's one tweak to make that even better: start outside the cloud (say, just some Linux VM's from Linode or whatever), then only if you get enough real customer/visitor demand to warrant easy/virtual scaling, then move to a cloud provider. Needing a cloud/elastic hosting provider is a bit of a Maserati Problem. If you get to the point where you have to build/manage your own data centers (like Google, Amazon, Orbitz), you have a Fleet-of-Maseratis Problem.
Netflix seems to be the biggest counter case - grew their data centers and effectively gave up and moved it to AWS. I suspect the sweet spot is doing a bit of public and private cloud, adjusting how much is on one or the other based on costs, service levels and capacity requirement volatility.