Amazon's same-day delivery option has been a boon to impatient shoppers in those few areas where it's available, and it's significantly expanding its reach today -- with one notable exception. The speedy shipping is now available in Dallas and San Francisco, letting locals get some of their orders on a given day by 9PM that night. If you're not an early riser, you'll also be happy to know that cutoff times for same-day ordering are getting later. Those in Dallas, Los Angeles, Phoenix, San Francisco and Seattle can purchase as late as 12:15PM and still expect a package by the evening. Indianapolis residents, meanwhile, can check out by 11:30AM instead of the previous (and not very realistic) 7AM.Amazon is also taking one step back for those two steps forward, though: Las Vegas has lost the same-day delivery option it got back in 2009. The company wouldn't tell the Wall Street Journal why, but it comes despite the presence of an Amazon warehouse in the area. Even with this odd reversal, it's clear that the company is determined to shrink shipping times as much as possible -- whether or not its experimental delivery network is ready for primetime.