I want to clear something up about WebSphere CloudBurst that can sometimes cause a bit of confusion. In nearly all of our content about the appliance, we talk about it in the context of building private clouds consisting of WebSphere application environments. Typically people think of private clouds as something only those within their organization can access and utilize. However, with WebSphere CloudBurst you are not limited to creating that kind of a private cloud.
Perhaps it is more fitting that we talk about WebSphere CloudBurst as a means to create on-premise clouds. After all, that's really what we mean. You create a shared pool of hardware and network resources owned by your organization, and then you define this cloud of resources to WebSphere CloudBurst. Once that cloud is defined, you can leverage WebSphere CloudBurst to dispense your WebSphere application environments into that cloud. The accessibility of your application environments running in that cloud is entirely up to you.
You may decide that the cloud is indeed private and that only those in your organization or a smaller subset of users can access the environments. On the other hand, you may decide that you want to allow consumers in the public domain to request WebSphere application environments and then have WebSphere CloudBurst provision those environments into a public cloud. I say public here because while the cloud's resources are on your premise, access to that cloud is not restricted to within the organizational firewall. Ultimately, the determining factor for whether or not your WebSphere CloudBurst cloud is public or private is the network configuration you provide. If the virtual machines are associated with network resources that are publicly accessible, then I would say you have a public cloud.
I hope this entry didn't serve to only add to the confusion. The bottom line is this: WebSphere CloudBurst allows you to create, deploy, and maintain virtualized WebSphere environments in an on-premise cloud. Whether that cloud is public or private is entirely up to the network configuration that you setup.