Vendor lock-in : Development according to the particular vendor can be easy but migration to another cloud provider can be a problem.
Data privacy : Corporate data, whether can be important or not, will always be private. It should always be an insecure environment.
Synchronization of system applications : We have integrated many applications with local and on the cloud, so there is the problem of increased complexity when mixing local data with cloud data.
Most PaaS cloud providers are Salesforce, Windows Azure, and Google App Engine etc.
