As first reported by 9to5Mac and then confirmed by MacRumors, Apple retail stores are now matching competitors' prices on iPads, iPhones and Macs. News of in-store price matches first started to crop up over the weekend, but now it appears that Apple has set an official company-wide policy for the procedure. As MacRumors notes:
According to a retail employee, Apple now has an official policy on price matching, which allows specialists to price match iPhones, iPads and Macs, giving up to 10 percent off on products without authorization. Specialists are also allowed to give business customers up to 20% off a non-Apple accessory when purchased with an Apple product via special order.
If you find a third-party reseller selling a Mac, iPad or iPhone for more than 10 percent off, it's still possible for Apple stores to price match that, though a normal sales person will not be able to grant the price match without first discussing it with the store manager. Also note that price matches are only done for legitimate resellers who are advertising the discounts and not for items sold new on Amazon or eBay by individual sellers.