One of the major objections to cloud computing has been that it is not secure enough. There is some truth to it and it is not an easy matter to secure an entire enterprise in a public cloud. Given all the apprehensions about the security, privacy, legislation involved, it is safe to say that the deployment of public cloud computing in large enterprises remains a distant dream.
Having said that, I believe the public cloud can greatly benefit the individuals. Cost of ownership of a computer today is unnecessarily high for all the well known reasons. Having to pay only for the computing power, software licenses, storage and networking bandwidth that I actually use is a very compelling proposition. I think over a period of time people will begin to realize the value in cloud computing, just as they did when utility companies began to deliver electricity to the homes. There are some concerns that cloud computing could lead to loss of freedom to choose, but I think those can be managed by proper legislation and also by developing open cloud standards and bill of rights (http://wiki.cloudcommunity.org/wiki/Cloud_Computing_Manifesto).
Private clouds can benefit large enterprises which invest in enormous computing power, network bandwidth and storage. Companies like IBM are developing tools and technology to make it happen. Private clouds will address the security and privacy issues as well as the risk of cloud hosting company going down under. Given a large enough enterprise, private cloud computing can be as cost effective as public cloud computing.
Entities that can benefit from cloud computing: