How does Google define cloud computing

There really isn’t a solid definition for cloud computing, so Google tells us what it means to them:

We thought we’d provide some insight into what we mean when we say cloud computing, and how its advantages in cost and innovation continue to attract hundreds of thousands of companies of all sizes — from 2nd Wind Exercise Equipment to Genentech. We created our cloud by building an optimized system from the ground up: starting with low-cost hardware, adding reliable software infrastructure that scales, offering innovative applications, and working every day to improve the whole system. While the McKinsey study only considered the hardware cost savings of the cloud, there is tremendous customer benefit in all of these areas.

via Official Google Enterprise Blog: What we talk about when we talk about cloud computing.