It's unlikely that hordes of VMware, Citrix or Microsoft Hyper-V users will flock to open-source virtualization or cloud-computing platform as an \n\nalternative to the hypervisors and virtualized infrastructure-management software they've already chosen, analysts say. So where does open source \n\nfit in the cloud world? Think lock-in and migration flexibility.Cloud computing customers will want to investigate open-source cloud software for the same reason they are eager to have cloud-\n\ninteroperability standards developed to help them avoid being locked in to a single cloud vendor and to make it easier to integrate apps, virtual \n\nmachines or other elements from external clouds or those of its business partners, says James Staten, vice president and principle analyst at Forrester.More intriguing: There's a good possibility the introduction of a second major open-source cloud product, CloudFoundry, from the leading \n\nproprietary cloud vendor, VMware, indicates there will be a major structural change in the market for cloud computing that will make cloud services \n\nviable while cloud software becomes a commodity, says Chris Wolf, research VP at Gartner.Announced on April 12, VMware's CloudFoundry platform, an open-source platform-as-a-service (PaaS) product, aims to give developers an easy \n\nway to deploy applications without worrying about the underlying infrastructure. CloudFoundry runs on top of VMware's proprietary vSphere virtualization \n\nsoftware, but isn't locked into the same licensing structures. VMware will sell a proprietary version, and host or license others to host public \n\nproprietary versions of CloudFoundry, but will also offer the source code to customers wanting to develop their own PaaS platform, according to a \n\nblog \n\nannouncing the product from VMware CTO Steve Herrod.It's still very VMware-centric, and its open-source credibility has yet to be demonstrated, but an "Open PaaS" offering based on \n\nthe open-source Apache applications, Hyperic, Groovy and Grails products that VMware bought along with SpringSource expand the development \n\nenvironment and migration options for its customers, Wolf says. CloudFoundry will natively run apps built in Spring for Java, Rails and Sinatra for Ruby and Node as well as other Java frameworks. OpenStack and the Migration AngleThe other major open-source alternative is OpenStack, an open-source cloud platform built for NASA by Rackspace, which combined its proprietary products with NASA's \n\nprevious development on a cloud system. OpenStack is available as open source from the Openstack project as well as in \n\nproprietary, better-supported editions from Rackspace and from Cloud.com, which offers a part open, part-proprietary set of services called CloudStack. Cloud.com's version includes interfaces designed to \n\nconnect its clouds with Amazon's EC2 and supports hypervisors from VMware, Citrix and the open-source KVM. All those options make it more likely customers will be able to move applications, data and virtual machines from one cloud to another if they \n\ndecide to change service providers or platform vendors, but not a lot more likely, Staten says. Both interoperability standards and open-source platforms define too little about an application's requirements, connectivity and security to \n\nprovide a smooth transition, and likely won't for at least a couple of years, Staten says. Cloud Foundry does open the PaaS market by adding a big player that supports more than the .NET applications Microsoft's Azure does, Wolf \n\nsays. But it also sets the stage for a big shakeup in the cloud-computing market. VMware's Tricky Competitive BalanceVMware has had to maintain a careful competitive balance for years among the hosting providers to whom it both supplies software and \n\npotentially competes with in the services market, and with its parent company EMC, which partners closely with VMware's biggest competitors \n\nMicrosoft and Citrix. CloudFoundry software and the plan to offer it as a service upsets that balance by pushing VMware squarely into the service-provider market, \n\nwhich could drive a wedge between it and its biggest customers, Wolf says. That could splinter the market for cloud software about three-quarters of which runs on VMware products as those former partners look for \n\nless-conflicted arrangements. It could also signal that VMware executives see the cloud market consolidating in the near future as virtualization functions become more \n\ncommon and developers like VMware face a bigger challenge in making products customers are willing to buy separately from their operating \n\nsystems. That's why it took over management of the low-cost cloud-based Mozy online storage service from EMC, Wolf says. "Virtualization at the most basic level is a function at the level of the operating system and VMware is competing against an operating-system \n\ncompany," Wolf says. "It's ahead now but won't always be able to stay that way, so it has to move toward providing the infrastructure itself as well. \n\nCloud Foundry and Mozy are a way to set itself up as more than just a software provider." Follow everything from CIO.com on Twitter @CIOonline.