If anyone is concerned about the OpenSSL Vulnerability that was highlighted earlier this month, then pop along to the Security Advisory below:
http://www.vmware.com/security/advisories/VMSA-2014-0004.html

Updates for the majority of VMware products to combat the “Heartbleed” vulnerability is now available….. Please note that post upgrade of products, you will need to regenerate the OpenSSL certificates!

vCenter Serveer 5.5.1a information can be found here:
https://www.vmware.com/support/vsphere5/doc/vsphere-vcenter-server-55u1a-release-notes.html
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2076692