This is a topic that comes up a lot. For most companies, the Cloud is a pretty new concept and they are still exploring how they can benefit from it operationally and financially. They are, so to speak, in exploring mode. While interoperability and moveable Cloud will be critical in the long-term, it is not that important currently, especially if the Cloud provider doesn’t lock you into a highly proprietary way of doing things, e.g. boot images that only work in their Cloud (Amazon AMIs) or middle-ware that is proprietary to them (force.com).

Another factor is often completely overlooked and that is the data. Once you store a lot of data in a Cloud, it could take days if not weeks, to get it out again, particularly if the provider doesn’t offer a service where they allow customers to copy data onto some physical device and ship it to another provider. The physical network speed becomes the bottle neck. Make sure that you ask your provider if they provide such a service before you get completely locked-in.