Amazon has just launched a new service called Prime Now, which will let Prime members order "tens of thousands" of "daily essentials" for immediate delivery. Once you download the new app (on Android or iOS), you'll get the option of picking a one- or two-hour delivery between 6AM and midnight, with Uber-like tracking included. The fastest option will run $7.99 per order and two-hour deliveries are free for Prime members. The service looks like a response to Google's same-day Shopping Express launched last year, which offers same day (but not one-hour) delivery at $5 a pop, or $99 a year. Prime Now will operate exclusively in Manhattan to start, but Amazon has promised that it'll soon be coming "to a city near you."