The new mobile MacBook Air/Pro models are using Intel Ivy Bridge processors. As mentioned in what's dozens of Phoronix articles now, these latest Intel CPUs launched back in April already work well under Linux.
Intel's Windows driver is faster than the Linux driver and the Windows driver does OpenGL 4.0 while the Linux driver is at OpenGL 3.0, but aside from the inequalities to the Windows driver, the Linux support is quite good. I'm still quite fond of running the Intel Core i7 3770K CPU even after about two months of use, its performance is very good on the CPU side and quite good for its integrated graphics. It will be interesting to see how the Mac OS X graphics driver compares to Linux and Windows! (In the past, Linux has presented better graphics performance than Mac OS X.)
The new chipsets for Ivy Bridge also aren't vastly different from Sandy Bridge so I haven't had any other motherboard issues either with the new boards that I have tested thus far.
The higher-end Apple MacBook Pro laptops are using the NVIDIA GeForce GT 650M for discrete graphics. This Kepler-based notebook GPU should work with the NVIDIA Linux binary driver already, but with Nouveau it will still be a wreck. There is NVIDIA Kepler open-source support, but it currently requires extracting your own firmware, there's no re-clocking support at all, and a host of other limitations. For notebook users for the next couple of months that are using GeForce 600 graphics, you're really best off using the NVIDIA binary blob or staving off your new hardware purchase.
These MacBook Pro models with the GeForce GT 650M also still support the Intel HD 4000 "Ivy Bridge" graphics via a switching interface. Until at least X.Org Server 1.13/1.14 plus Linux 3.5+ and other yet-to-be-released code, the switchable graphics / NVIDIA Optimus support will continue to be a shit wreck under Linux for the near future.
On the "Next Generation MacBook Pro" is also the retina display with -- 5.1 million pixels at a resolution of 2880 x 1800 on a 15.4-inch panel. The NVIDIA Linux binary driver at least should be able to mode-set correctly while delivering decent performance with their proprietary driver, although this has yet to be tested under Linux. The Nouveau driver might mode-set correctly, etc, but the performance might be scary considering the current delta the Nouveau Gallium3D driver has to the proprietary driver at lower resolutions.
On the user-space side for Linux with retina displays, some projects like the Qt tool-kit have already been talking about how to best take advantage of these high-resolution displays.
Aside from hardware incompatibilities, the other potential inhibitors for Linux on the new Apple MacBook Air and MacBook Pro models come down to the UEFI, how well the power management works under Linux, suspend-and-resume, and other features.
Next month I'll likely end up ordering a MacBook Air or the next-generation MacBook Pro to see how well the latest Apple products work under Linux. I also have new Mac OS X 10.8 benchmarks (the forthcoming "Mountain Lion") that will be published soon from last year's Mac Mini; the results will be compared to Ubuntu Linux.
With my current main business laptop, it's a 2010 Apple MacBook Pro with OS X and then it runs Ubuntu Linux (10.10) virtualized using VMware since I actually get better battery life when virtualizing Linux than running it bare metal on the hardware. Let's hope this is another changed "feature" to be found with the 2012 Apple MacBook products.