As pointed out on RevoGirl's blog, evidence of unreleased Macs can be found in the Mountain Lion Developer Preview in /System/Library/Extensions/AppleHDA.kext/Contents/Resources. There's a bunch of XML files in there corresponding to different Macs and their default audio configurations, for example their settings when accessing System Preferences -> Sound, and some stuff you aren't supposed to change like the default volume of the booting sound, etc. The latest Lion version has configuration files for 76 Mac models. Mountain Lion has 9 extra files for unreleased Mac models. Here is a summary of those files and their keys: Opening the files in Xcode make you see some extra keys and their values, but nothing really interesting for making guesses about upcoming Mac models. From the list up there, we can assume layout85 and layout86 are for the new MacBook Airs, as they have an integrated Mic but no SPDIF (optical audio) input/output. Layout83 is probably for a new iMac, as it has SPDIF in/out and an integrated Mic, and layout 88 is probably the new Mac mini as it has SPDIF in/out but no integrated mic. That leaves us with 5 files. I'm not sure what layout90 and layout92 are, but we know they're not laptops since they don't have an integrated mic. They could be Mac Pros or a completely new line of Macs. We're left with 3 files that are laptops: layout40, layout59 and layout 82. MacBook Pros seem like a logical guess. Now that would confirm two things: - 3 different audio configuration files suggest 3 different models (sizes) for the new MacBook Pro. - The fact that, unlike current MacBook Pros, they don't include keys for SPDIFIn and LineIn suggest that all 3 models wouldn't include a dedicated audio line in. Currently, only the 13" MacBook Pro doesn't have a dedicated line in. However, it supports SPDIFOut (optical audio out) through its combined in/out 3.5mm audio port. Those 3 new Mac laptops appear to have a single combined audio jack that supports optical audio out only, without optical audio input support, just like the current 13" MBP. Current 15" and 17" MBPs support optical audio both ways while the MBA doesn't support it at all. That supports the idea of a completely redesigned MacBook Pro, which would come in 3 different configurations (sizes), which would all have a combined in/out audio port, similar to the one on the current 13" MBP.