CloudBzz frames the issue this way:

But PaaS before this week meant lock-in. Developers, and the people who pay them, don't like to be locked into specific vendor solutions. If you write for Azure, the fear (warranted or not) is that you can only run on Azure. Given that Microsoft has totally fumbled the opportunity to make Azure a partner-centric platform play, that means you need to run your Azure apps on Microsoft's cloud. Force.com is even worse - with it's own language, data model, etc. there's not even the chance that you can run your code elsewhere without major rework. Force.com got traction primarily for people building extensions to Salesforce's SFA and CRM offerings - though some people did do more with it. VMforce (Spring on Force.com) was supposed to change the openness issue by providing a framework for any Java apps to run. Google AppEngine is also proprietary in many respects, and when it launched with just a single language (Python!), a lot of developers shrugged. Even the proprietary PaaS components of AWS have been a problem. I could not get my developers to use SimpleDB back in 2008 because, as the rightly pointed out, we'd be stuck if we wanted to move off of EC2 at some point.

It's fair to say that many believe VMware has created something that is open and viable for the enterprise. It allows for the flexibilities that developers demand but has the controls in place to satisfy the enterprise guards.

What does Cloud Foundry represent? Do you think it will it be a disruptive force in the market?