It looks as though future iMacs and Mac Pros may come without optical drives. AppleInsider has found hints pointing to internal configuration files in Mountain Lion. According to the site:
Internal configuration files in Mountain Lion make apparent references to yet-unreleased new generations of Apple's iMac (iMac13,0) and Mac Pro (MacPro6,0), both in the context of USB booting options that indicate the new Mac desktops could, for the first time in nearly 20 years, lack built-in optical drives.
The discovery, made by an AppleInsider reader Jason, appears in a configuration plist file used by Boot Camp Assistant to designate the Mac model versions capable of supporting either a optical boot disc, or alternatively, a USB flash drive volume capable of installing Windows to a Boot Camp partition.
The appearance of new Mac Pro and iMac models in the USB booting support list doesn't definitively mean the models won't have optical drives, as it also lists MacBook and MacBook Pro models that do incorporate an optical drive.
At the same time, Apple has clearly indicated in the newest Mac mini and Retina Display MacBook Pro that it plans to get rid of optical disc drives as soon as possible across the board, providing an external USB drive as an option for users who need one.
Users increasingly have fewer opportunities to use optical drives, as the bulk of third party software is now available as a digital download either directly from the vendor or through Apple's App Store. Apple also sees digital distribution as the future of music and movies, as exemplified in Apple TV, which has never included an optical drive.
Modern Mac models can now apply system updates, such as OS X Mountain Lion, entirely via digital downloads, while Apple's newest Mac models can boot legacy operating systems from USB flash drives.
By ditching the need for a built in optical drive, Apple can not only make new Macs smaller, thinner and more energy efficient, but will also increase their overall reliability, as optical drives become one of the last complex physical mechanisms inside computers.
Read the full story on AppleInsider here.