1. A system for providing virtual desktop extensions on a client desktop, comprising: a virtual desktop extension manager in communication with a client machine having a desktop interface, and in communication with a cloud computing environment, wherein the virtual desktop extension manager is configured to: receive a request from a local application executing on the client machine, wherein the request identifies one or more virtual desktop extensions available to the client machine in the cloud computing environment; receive authentication credentials for the client machine from a credentials cache locally coupled to the client machine; determine whether to cause one or more virtual machine instances that host one or more identified virtual desktop extensions to be launched in a public cloud computing environment or to be launched in a private cloud computing environment; and cause the cloud computing environment to launch the one or more virtual machine instances that host the one or more identified virtual desktop extensions in one of the public cloud computing environment or the private cloud computing environment in response to determining that the authentication credentials received from the credentials cache indicate that the client machine has access to the one or more identified virtual desktop extensions, wherein the one or more hosted virtual desktop extensions are displayable by the local application executing on the desktop interface for the client machine.