Back in May I mentioned VMware was working on the Virtual Machine Communication Interface for Linux and back then their kernel patches were in a "Request For Comments" state. The patches have been revised and now VMware is lining up the VMCI support to enter the mainline kernel, hopefully for the Linux 3.6 kernel.
As said in the mailing list message concerning VMCI for Linux, "VMCI allows virtual machines to communicate with host kernel modules and the VMware hypervisors. User level applications both in a virtual machine and on the host can use vmw_vmci through VMCI Sockets, a socket address family designed to be compatible with UDP and TCP at the interface level. Today, VMCI and VMCI Sockets are used by the VMware shared folders (HGFS) and various VMware Tools components inside the guest for zero-config, network-less access to VMware host services. In addition to this, VMware's users are using VMCI Sockets for various applications, where network access of the virtual machine is restricted or non-existent. Examples of this are VMs communicating with device proxies for proprietary hardware running as host applications and automated testing of applications running within virtual machines."
Find out more information in this kernel mailing list thread.