Enterprise software pundits are now gazing metaphorically skyward. There’s all this talk of clouds, but what kind of clouds are coming, and will they be friendly? We begin by describing some applications we’ve developed for App Engine, including implementation of other languages, such as JRuby, on top of the App Engine for Java implementation. These implementations demonstrate the breadth of capability provided by App Engine. We then examine some of the strengths and current weaknesses that we encountered. We also describe more about the implications for testing that arise when developing on App Engine. We will also present an initial framework for characterizing these differnet clouds and examine how these characteristics will impact the adoption path for enterprises and the kinds of applications these enterprises will move to the cloud. Of particular interest here is the central role of Big Table in App Engine. Broad adoption of this of this platform could lead to lots of lightening striking at the dominant role relational data base systems currently enjoy.