I didn't see this advantage, but my Web application had just one class and one JSP. The Web interface to Jenkins comes with a neat progress bar and a flashing blue ball that made it clear that my local machine could build these few files faster than the leviathan in CloudBees' data center.
Even if small projects won't tap the power of the cloud, they'll still be able to use the discipline of Jenkins. It took me a few minutes of poking and prodding to get the code to flow all the way through the build pipeline, but after that I was golden. It's nice to let someone else worry about keeping Jenkins running.
The CloudBees cloud is essentially Tomcat and MySQL, but other databases are available, including some from third parties with tight integration. Cloudant, for instance, offers CouchDB services, and MongoHQ serves up MongoDB.
CloudBees offers servers as "app cells," a unit of power that's roughly one-eighth of a standard Amazon EC2 server. The memory and compute cycles are tied together, so you essentially buy the servers by the eighth.
CloudBees offers a generous set of free services, but the constraints are tight. Only the casual developers will be happy within them. Anyone engaged in serious work will quickly need to upgrade to a paying service.
Java clouds: Red Hat OpenShift Red Hat was never content to be just a collection of Linux tools. Its new foray into the cloud, called OpenShift, offers a quick way to deploy Java, Python, PHP, or Ruby apps to a collection of machines waiting to accept them. When you're done developing, the Red Hat cloud offers a collection of tools for deploying your app on Amazon EC2.
OpenShift is not Java-centric by any means. Whether you create a Java app or another kind, it handles much of the deployment issues. The standard Java application is a JBoss Application Server 7 stack built by Maven. This is a fairly new option, and I didn't find it listed in the fancy HTML documentation. Instead, I stumbled on it by hitting -h on the command line.
Yes, OpenShift is a good tool for those who like to use the command line. I typed a few lines, and boom! A JBoss application was deployed, running, and ready for customization. Updating is also simple. After you add lines, you commit to Git and push to the main server. This is more than a typical push, though, because you can watch the Maven build executed automatically as the push triggers a deployment. Using a version control system to run a deployment is more and more common, especially because it makes rolling back easier. Choosing Git is a modern choice.