The cloud looks less cloudy by the week. This week's story line for the VMworld 2011 conference in Las Vegas, which opens today, appears to be "cloud definition." One of this week's most defining moments may have already happened, as Citrix Systems made good on its pledge last month, in acquiring cloud infrastructure firm Cloud.com, to extend its CloudStack infrastructure platform to a broader array of customers.

This morning, now that Cloud.com has completely been absorbed into Citrix, the cloud infrastructure project is announcing it is completely folding its commercial tier into the open source community. This makes CloudStack officially 100% FOSS. What's more, the latest version will add support for Oracle VM hypervisors, in addition to its existing support for VMware vSphere and Citrix XenServer. Preview release 2.2.11 is available now (warning: it cannot be used to upgrade GA installations).

"We're introducing bare-metal provisioning into the product," adds Peder Ulander, in an interview with RWW. "This is specific to enterprises interested in having cloud-like functionality delivered on top of bare metal, versus using virtualization. And finally, we're publishing a roadmap that gives us [Microsoft] Hyper-V support by the end of the year." Ulander led Cloud.com, and now leads CloudStack for Citrix.

"What we bring is a fairly open, robust, high performing cloud platform that competes aggressively with vCloud," Ulander adds. "By CloudStack as your cloud operating platform, you now have the opportunity to have one of the top cloud platforms already running in your VMware environment, with all of the tools, knowledge, and experience that you know, but you can also mix and match additional virtualization technologies into the platform, so now you can prioritize workloads and budgets around business needs."

Citrix had already been heavily invested in one open source vSphere competitor, OpenStack, as the cornerstone of its Project Olympus which also incorporated a cloud-optimized XenServer. After last month's Cloud.com acquisition, observers pondered just what Citrix would be planning with both OpenStack and CloudStack, and whether the former would fall by the wayside. As it happens, the two projects are seeking greater alignment with one another, and OpenStack leaders have shown nothing but praise for their new brethren.

Writes former Citrix CTO Simon Crosby, who left that company in June to form his own startup called Bromium:

Everyone knows that the future for proprietary cloud stacks looks rather bleak, given the enormous industry focus on developing a community owned, massively scalable open source cloud stack - OpenStack. Cloud.com was therefore quick to jump aboard the OpenStack community development model, and has led some of the key contributions to OpenStack, including support for Hyper-V. Citrix can use the cloud.com acquisition to accelerate its own Project Olympus, which will be OpenStack based, and in so doing it can offer existing cloud.com customers a roadmap that is far richer than could ever be created by a single vendor following its own development path. Future versions of CloudStack (or whatever it ends up being called) will be able to scale better and offer a far richer networking model, storage infrastructure and so on, courtesy of the incredible contributions being made by over 50 vendors to OpenStack.

CloudStack's strategy is to restore warmth and good feelings to the "embrace and extend" metaphor. "If you think about the way clouds are built today," Peder Ulander tells RWW, "you have underlying hypervisor technologies and then you layer in more administration and management on top of that. Every single company that I've engaged with has a multi-vendor hypervisor cloud approach, meaning that they will most likely have an open source cloud and a VMware cloud. The open source cloud is designed to create more predictable, manageable business models. So for customers who are running VMware, if they go down the vCloud Director path, they are locked into one cloud platform, and their open source platform becomes completely different. They're managing two sets of resource pools, two sets of data center environments, two sets of interfaces, two sets of applications."

So CloudStack will run completely on top of vSphere for free, the Citrix VP explains. Customers will then have the option to continue to run on VMware, or to fold in additional hypervisor functions from KVM, Hyper-V, OVM, or XenServer within the same architecture.

"Citrix has always had the fundamental belief that customers want choice in virtualization. Therefore, technologies like XenDesktop and XenApp have always been available on technologies like VMware. In fact, the leading desktop platform on top of VMware is actually from Citrix. At Cloud.com, we were already building this functionality into the product - multi-hypervisor capabilities. But as a 40-person startup with a limited budget, we weren't able to get the message out as far. Today, Citrix's biggest message coming in is, 'We never met a hypervisor we didn't like.'"

Perhaps CloudStack's highest-profile customer to date has been Facebook games developer Zynga, the creator of virtual little-people "-ville" worlds. As analyst David Cahill wrote earlier this month, Zynga had launched its games service on Amazon's EC2 cloud, but quickly discovered it couldn't support the tremendous volume. Using CloudStack (which isn't actually named in Cahill's report, but is implied), Zynga was able to construct its so-called zCloud infrastructure, and later manage it using RightScale commercial provisioning software, which Cahill says can spin up 1,000 new servers in 24 hours.

Building new Zynga-scale customers in record time means Citrix needs to implement some very creative training - a personal angle which Ulander contends his commercial competitor fails to provide.

"When it comes to VMware View, vCloud Director, or even Cloud Foundry, there is no training, certification, or education from VMware on those technologies. Those customers are getting a little bit of frustration from the fact that that higher-level pieces that are helping them move their businesses forward are not as clean and as easy as where they stand today with their core virtualization platform. For that reason, we see an opportunity."

Citrix will be offering customers "Build-a-Cloud Days" on-site training for negotiable fees, as well as inviting them to attend these trainings for free at trade shows - for instance, Ohio LinuxFest, scheduled for next week in Columbus.