We know they're coming, but they're shrouded in the same secrecy that everything Apple makes... but it looks like we should expect new Mac Pro and iMac models soon. AppleInsider is reporting that internal configuration files found in the recently released Mountain Lion are pointing toward unreleased new-generations of Apple's iMac (iMac13,0) and Mac Pro (MacPro6,0).
Both have hinted at USB booting options, where we could see the first time in close to 20 years, with Mac desktops without built-in optical drives. The discovery was found by a keen-eyed AppleInsider source, who found the details in a configuration plist file used by the Boot Camp Assistant to designate Mac model versions capable of supporting either an optical boot disc, or a USB flash drive volume capable of installing Windows to a Boot Camp partition.
We've had hints at updated Macs, but I'm guessing we should expect a Retina-powered iMac, as it would make the most sense right now. The Mac Pro, I hope gets a serious injection of performance over previous generations of Mac Pro's, as it is much needed when compared to the competition from other vendors such as HP, and Dell.