VMware Security Certifications & Validations (see also the guides tab for hardening guides)
https://www.vmware.com/support/support-resources/certifications.html
résumé
VMware ESX 4.1, ESXi 4.1 and vCenter Server 4.1have achieved Evaluation Assurance Level 4+ (EAL4+)certification in December 2010. 
VMware vSphere 5.0 has achieved Common Criteria Certificationat EAL4+: 
Le reste en cours

VMCI sockets
http://www.vmware.com/support/developer/vmci-sdk/
pdf et lien http://pubs.vmware.com/vsphere-51/topic/com.vmware.vmci.pg.doc/vsockPreface.html
http://pubs.vmware.com/vsphere-51/topic/com.vmware.ICbase/PDF/ws8x_esx51_vmci_sockets.pdf

VMCI SDK (old truc)
http://pubs.vmware.com/vmci-sdk/
http://www.phoronix.com/scan.php?page=news_item&px=MTI3MTE

good old backdoor
https://sites.google.com/site/chitchatvmback/backdoor
http://articles.sysprogs.org/kdvmware/guestrpc.shtml / http://articles.sysprogs.org/kdvmware/guestrpc/
prez HSC http://www.ossir.org/sur/supports/2008/OSSIR_VMware_20080807.pdf

vsock / vmci in kernel
https://lwn.net/Articles/481611/
https://lwn.net/Articles/531950/

Subject: [RFC 0/5] Introduce VM Sockets virtio transport http://www.spinics.net/lists/kvm/msg93288.html

Unrelated, but interesting: http://trac.evolix.net/infogerance/wiki/ServeurVMware