The cloud offers distributed resources, but as a general principle it's good to bear in mind that those resources are no more or less invulnerable than any other resources. Cloud-based companies can suffer outages the same as ground-bound ones -- precisely because cloud-based firms, of necessity, are bound to the same sorts of resources as everyone else. Servers, connections, software, personnel can all be sources or causes of outages. Too much confidence in the cloud can make even occasional, brief outages a source of outrage, as witness recent Gmail glitches. Before committing to a cloud service or provider, be sure they've provided you with documentation detailing the availability rates they guarantee (less than 99+% is unacceptable), their remedies and remediation strategies should an outage occur and their responsibility for any liabilities your business might incur as a consequence of a cloud-outage.