Originally Posted by wizard69
As the subject says a waste of time to put in hardware to run iOS apps. The big issues are marketing and consummer confusion. Also from the engineering point of view it is a complete waste, an Intel processor can easily emulate an entire ARM based machine.
While that might be true, a real ARM CPU would be a much better choice to add iOS app compatibility. Performance would be much more predictable and closer to an iOS device with the same chip, and power consumption would be much lower than emulating in software. Last but not least the A4 chips also have a GPU on them, and emulating an embedded PowerVR GPU using a desktop-style Nvidia GPU (this includes the ones in Apple laptops, as far as GPU architecture they are nothing like the PowerVR) without completely screwing up the performance characteristics (and thus compatibility) would be near impossible. Just look at how the iOS simulator works for debugging graphics-related bugs and performance issues, it's near useless compared to running on the device itself.
Throwing in the same A4 chips as found in the iPhone 4 would be dirt-cheap for Apple as well, by now they can probably source them for under $5 a piece.
As a side not there are likely a number of ARM processors all ready in Apples Macs. ARM core are often embedded in support chips.
The fact that there might be some chips based on ARM cores in Macs (I can only think of the network controller) is kind of meaningless for iOS compatibility because you couldn't use them for running anything on them besides the firmware for the part they are running, and they would be heavily customized parts based on older ARM instruction sets and with everything stripped out that's not needed for their job.
The answer is never. Atleast not in the sense you want to see them implemented. The sad reality is that ARM CPU cores aren't even close to intel performance wise.
ARM replacing x86 for Macs is not going to happen anytime soon (I wouldn't say 'never' though, there's some crazy fast quad-core ARM chips announced for 2012 already). But an ARM coprocessor for iOS application compatibility wouldn't be unlikely at all, in fact, I've been hypothesizing this since the first rumors of the AppleTV running iOS applications.
If Apple would manage to pull of some really impressive engineering trick such as a switchable x86/ARM OS X version that you could boot or even run-time switch to whatever you need at the time, they could sell you a MacBook Pro that would be as fast as ever when using the Intel part, but could also last 20+ hours on the ARM part when you are on the road. Imagine how long you could run a 10W ARM chip off of the MacBook Pro battery