Boris Renski, cofounder, Mirantis Twitter/@zer0tweets PayPal and eBay are yanking VMware software from some 80,000 servers and replacing it with the free and open-source alternative known as OpenStack, Boris Renski, OpenStack Foundation board member told Business Insider.

Renski is also a cofounder of Mirantis, an OpenStack consultant company backed by Dell and Intel. Mirantis worked with PayPal on the project, he says.

PayPal used a set of tools from Mirantis called Fuel, a PayPal spokesperson told us.

Today Mirantis released Fuel for free to the public. (In geek speak: it was released under the open source Apache 2.0 license). It's a collection of scripts and software that helps companies deploy OpenStack.

Initially, PayPal is replacing VMware on about 10,000 computer servers. Those servers will go live this summer, Renski said. "The grand vision for project is, over time, they will replace all of their virtual infrastructure with OpenStack, not just PayPal, but PayPal and eBay, together," Renski said. That's about 80,000 servers across their data centers, he said.

PayPal has been a big supporter of OpenStack for a while. But this project is still dangerous territory for VMware, as PayPal could become an example of how other enterprise can replace VMware with OpenStack, too.

To be sure, enterprises are not dying to get rid of VMware, even to save money on software license fees. Most of them really love VMware's software because it's a reliable way to run lots of different applications on the same computer server.

But cloud wars are coming between different so-called "cloud operating" systems: VMware is up against OpenStack (backed by IBM, HP, Rackspace, Red Hat, others) and CloudStack (another open source project, backed by Citrix).

Think of this like the desktop operating system wars: Windows vs. Macs vs. Linux.

The ultimate goal for most enterprises is something called a "hybrid" cloud. This means that a company will run some of its apps in its own data center (a "private cloud") and some of them in a public cloud. They can easily move apps between the two.

More importantly, they can use multiple public clouds. If one provider has problems, they can quickly switch to another.

Enterprises will have to choose their cloud operating system and the stakes are high. Enterprises will spend $80 billion on cloud computing by 2016, Gartner estimates.

So where does the biggest cloud player, Amazon, fit into all of this? Amazon is the reason for it all. These cloud operating systems rose to compete with it. The idea is to reassure enterprises that they if they choose an alternative to Amazon, they will have lots of cloud computing vendors to choose from, not just one.

UPDATE: We have heard from Adrian Ionel, the CEO of Renski's company Mirantis, who says that Renski is "exaggerating the use case" of OpenStack at PayPal and that Renski's "knowledge of the project is second hand and therefore limited." Renski's title at Mirantis is executive vice president.

PayPal also sent us these comments to questions we had previously asked: