Broadly speaking, there are two sets of questions you want to answer:
1. The "really?" set of questions: Is the cloud what you really need? If so, can you architect your system to exploit the advantages of the cloud?
2. The "how?" set of questions: do you outsource the cloud to AWS et al or do you build your own? The details of this are probably worth half a book, but there are many databases to choose from (CouchDB, MemcacheDB, Tokyo Products and LightCloud, thrudb, Project Voldemort, redis, and others) and build-or-manage-your-own cloud computing datacenter (EUCALYPTUS, AppScale, Enomaly, ELASTRA, 3tera, etc).
The answer to these questions starts with "what are you trying to do?" In many cases, the cheapest and fastest way to get going is to provision some virtual servers from Linode or Slicehost and have a go. If you grow too much, 1. congratulations and 2. look at the cloud options.
1. The "really?" set of questions: Is the cloud what you really need? If so, can you architect your system to exploit the advantages of the cloud?
2. The "how?" set of questions: do you outsource the cloud to AWS et al or do you build your own? The details of this are probably worth half a book, but there are many databases to choose from (CouchDB, MemcacheDB, Tokyo Products and LightCloud, thrudb, Project Voldemort, redis, and others) and build-or-manage-your-own cloud computing datacenter (EUCALYPTUS, AppScale, Enomaly, ELASTRA, 3tera, etc).
The answer to these questions starts with "what are you trying to do?" In many cases, the cheapest and fastest way to get going is to provision some virtual servers from Linode or Slicehost and have a go. If you grow too much, 1. congratulations and 2. look at the cloud options.