The easiest way to use Cloud Foundry is to create a Spring project from a template with SpringSource's customized version of Eclipse called the SpringSource Tool Suite. I tried installing some of SpringSource's tools into my own version of Eclipse, but the right collection of libraries was not easy to find. The SpringSource Tool Suite is simpler.
The Cloud Foundry is not limited to Spring. There's support for Rails, Sinatra, Scala, Grails, and Node.js. It's all running on the JVM even if you don't write any Java. Cloud Foundry just announced PHP and Python/Django support as well. The VM image that you get also comes ready with MySQL, MongoDB, and Redis databases waiting to suck up your information.
VMware has kept mum about the pricing. The product is still in beta, and VMware has been kind enough not to charge for it. Will the rates be too high? How can you plan? You can't, but the Cloud Foundry virtual machine is fairly open. You can download the Micro Cloud Foundry -- a portable virtual machine image of the Cloud Foundry environment -- and run it on your own system with VMware Player. The core code is open sourced at cloudfoundry.org and largely covered by the Apache license.
Java clouds: CloudBees One joke floating around the Net is a list of lies that companies tell potential hires to seem more with it. Running a continuous integration server is near the top. Everyone likes the idea of constantly checking the code to make sure it works, but no one wants to do all of the work required to both maintain the code and keep the continuous integration server up and running.
CloudBees would like to change this. Not only does the company offer a cloud for deploying your applications, but it provides a cloud to build them too. Your account is more than just a way to serve your data to the masses. There's a code repository (Git or Subversion) and a Jenkins server watching every piece of code you check in.
After a bit of fiddling, I was able to check in code and wait for Jenkins to build it, test it, compile the documentation, and deploy it to the server. If I needed more, there were plenty of other services, plug-ins, and switches to flip.
The theory is that CloudBees has plenty of high-end boxes working in parallel to build your huge pile of code. Instead of waiting for your desktop machine to page in the right libraries, you can let Jenkins parcel out your build to the racks at CloudBees.