Amazon introduced EC2 back in 2006. Since then, additional vendors introduced similar public cloud offerings. As a result, new applications and businesses were created based on the new features, cost and business models that these public clouds are offering. The question of private vs public deployments keeps being considered in many new as well as existing applications. The simple logic of "this deployment costs X in private data center and 3X in public cloud deployment" is missing some of the key consideration like: agile architecture changes, flexible consumption models and will likely lead to wrong conclusions. This talk will focus on a several considerations, based on real life experience, on when it makes sense to use the private data-center and when to use the public cloud.