After working with VPS hosting for several years, and starting to build larger infrastructure proposals with virtualization and 'cloud' resources in mind, this particular paper is going to be very useful. We have already been running into serious portability, security/compliance, and QA issues. Nevertheless, since we have a pulse, we can still see how kick-a** the price points are, and would much rather work through these issues in a community rather than bumble around with them ourselves. Just try to move an EC2 instance to Slicehost, or vice versa, and then try to get any piece of your proposal through the compliance lawyers, and you'll feel the burn.