Since being named senior vice president for Google's cloud businesses, Diane Greene appears to have been busy: Spotify very publicly switched over to Google's infrastructure after several years with Amazon, and now Apple has quietly moved as much as $600 million of an estimated billion dollar annual cloud to Google.

It's tough news for Amazon's AWS, which just celebrated its 10th anniversary as the market leader, but one facing customers increasingly worried about lock-in and how well Amazon's costs scale with the size of the business.

In addition to Amazon, Apple also uses Azure for some of its data hosting, although the company says most data is hosted in its own datacenters.

Amazon might be taking the move personally: The day before the news about Apple's move leaked, Amazon touted in a new release that over a thousand databases had migrated to AWS since January 1st, including Expedia and Pegasystems.

Combined, that's a lot of business, but losing a $600 million deal means Amazon has a lot of extra space to fill.