The first stable version of Qubes OS has been released Monday by Polish security firm Invisible Things Lab. The operating system is designed to provide a greater level of security by isolating programs inside virtual machines with different permissions. Applications can be configured to run inside different “security domains” defined by the user and which are implemented as lightweight virtual machines (VMs) Qubes offers more flexibility and doesn’t rely as much on security choices made by its developers. Qubes is based on Linux, the X Window System and the Xen hypervisor — a virtual machine manager.”]