The Linux Foundation, a non-profit organization focused on accelerating the growth of Linux as an Operating System, announced today that VMware has become a member of the foundation.
As you all know, the ESX hypervisor is based off of Linux, so it was probably only a matter of time before VMware joined the Foundation.
“We are delighted to become a member of The Linux Foundation and look forward to making future contributions to the Linux community,” said Dan Chu.
There is a rumor that VMware may open the source of the already free VMware Server product.
As a big-time linux user and fan, I am pleased to welcome VMware to the Linux Foundation. I think their contributions will really help move Linux forward.

This is good news! However, you are severely misinformed.
ESX is a completely proprietary, custom, non-xnix kernel.
My mistake. It is however Linux based. But yes, you are correct… it is not a Linux kernel.