Still in "limited preview," Google Compute Engine doesn't have a firm launch date yet, but the basic outlines encourage comparisons with Amazon EC2 -- though it'll take years to catch up with Amazon's feature set. As a jump-start, Google may turn to partners, as it has to MapR for Hadoop services.
Google's main marketing point is "consistent performance," a not-so-subtle dig at Amazon, which has been known to annoy customers with slowdowns. The company will also offer data encryption by default, including data at rest, which should assuage some customers' cloud security concerns. And of course, there's Google App Engine, one of the leading PaaS offerings on the Web, supporting Python, Java, and Google Go.