Amazon deliveries keep getting faster. On Tuesday, the online retailer announced the launch of its 30-minute delivery option, dubbed “ Amazon Now, ” in dozens of U.S. cities. This ultra-fast delivery option will allow customers to shop across “thousands” of items, Amazon says, including fresh groceries, household essentials, and other locally relevant items. At launch, Amazon Now will be widely available in Atlanta, Dallas-Fort Worth, Philadelphia, and Seattle, and is expanding to Austin, Denver, Houston, Minneapolis, Orlando, Oklahoma City, and Phoenix. By year-end, Amazon expects to bring the service to tens of millions of customers in these and other cities, as the rollout continues across the U.S. The eligible items will be flagged with “30-minute delivery” banners in the Amazon app and website. Amazon Now offers will also be displayed to customers as they shop.…