multicore gizmos
'Multicore' processors are pretty new - older machines have always had an enormous number of processors. 80 cores on a single chip would take up most of the silicon wafer. (and will probably have a few defective cores and rather interesting cooling problems)
Problems encountered by multiple processors include - how do you know that another processor altered data? This is especially important when multiple processors are using their 'cache memory'. So the processors need special hardware to signal eachother.
So for question #1:
Shouldn't take long at all - Linux habitually handles '8-way' Opterons and way back around 2003 the operating system structures were tweaked to allow some ridiculous number of processors (which we're still skeptical of being met, but strange things happen). The biggest job is adding support into the compiler and the next biggest job is writing the assembly portions of the Linux kernel. Of course some poor creature will have to study the documentation on the candy-bar computer and figure out exactly how its features can be exploited by the kernel.
for Question #2:
Microsoft will seriously struggle - there are numerous defects in the system and we always have a good laugh when Microsoft talk about reliability, 'high performance', and 'scalability'. WinDos cannot even handle time properly; in contrast, UNIX was handling time even before DOS was out on the market (allowing every user to have their own time zone - in fact any program running can have its own time zone).
Apple's OSX is based on BSD, which will currently run on at least '8-way' machines. I don't keep in touch with BSD developments so I don't know what their current limit is.
Of course more cores doesn't mean a faster machine unless you do things in parallel. It may be great for servers which do a lot of actual processing and in astronomy for 'multibody' calculations (and in physics for 'Monte Carlo' simulations of light scattering) but for most purposes it will just keep the room that little bit warmer.
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