We are developing MobiDesk, a mobile virtual desktop computing hosting infrastructure that leverages continued improvements in network speed, cost, and ubiquity to address the complexity, cost, and mobility limitations of today's personal computing infrastructure. MobiDesk transparently virtualizes a user's computing session by abstracting underlying system resources in three key areas: display, operating system, and network. It provides a thin virtualization layer that decouples a user's computing session from any particular end-user device, and moves all application logic to hosting providers. The virtualization layer decouples a user's computing session from the underlying operating system and server instance, enabling high-availability service by transparently migrating sessions from one server to another during server maintenance or upgrades. We have implemented a prototype in Linux that works with existing unmodified applications and operating system kernels. Our experimental results demonstrate that MobiDesk has very low virtualization overhead, can provide a full featured desktop experience including full-motion video support, and is able to migrate users' sessions efficiently and reliably for high-availability, while maintaining existing network connections.