For a little while now VMware has been talking about vFabric - its "Cloud Application Platform" that comes as a result of several acquisitions. vFabric is an emalgam of serveral different technologies from SpringSource, GemFire, Hyperic and RabbitMQ. At first this may seem like a boxed platform-as-a-service (PaaS) offering... but ultimately it isn't quite there.
You may remember the launch of VMforce back in April - VMware's first forray into PaaS. Here Salesforce.com took VMware's aquired technology stack and ran with it, creating a platform that combined vSphere, tcServer and Spring. VMware's initial take was that this was to launch their "Open PaaS" strategy, the harbinger of coming PaaS launches that allowed for inter-operability between all kinds of clouds. The promise appeared to be the cloud version of "write once, run anywhere."
Salesforce.com then added their own JPA sources and annotations to leverage their own CRM databases, content and services to be leveraged by applications running on this platform. This makes portability a bit more of a sticky subject, since data sources or chat services leveraged on VMforce don't necessarily translate to other SpringSource platforms. It seems (to me at least) that this has made VMforce a bit of an island unto itself, not necessarily an initial launch of an inter-operable PaaS platform.
So where does vFabric fit in? At this point vFabric is just the sum of its parts; a collection of bricks that don't actually construct a larger product just yet. You might notice that the terms "PaaS" or "Platform as a Service" doesn't appear in VMware's vForce announcement. Rod Johnson notes in his vFabric announcement post that the current emphasis is currently about enabling AppEngine and Force.com to operate with the Spring IoC programming model; it doesn't appear to focus on creating a ready-made PaaS offering.
I'm not saying that a Java PaaS offering isn't the end game... it may well be... but as of yet there is nothing you can install and have an elastic cloud for application hosting. The acquisition of tcServer and GemFire may yet make this a reality, but time will have to tell.