What currently-available hardware isn't supported in Win8?
USB 3.0 is one of the big additions. (Whoopee-do - what a major accomplishment.)
Vista used native SATA drivers for the first time, despite SATA's availability for about 5 years, including the initial WinXP release. It was still too new for HW manufacturers to 'standardize' so, fine, XP does without.
What's Win8 'doing without'?
Thunderbolt? That's all I can think of.
Win7 no longer natively supports my precious HP Deskjet 972 - not out of the box, but a WinUpdate does that just fine. Wheee - I can still print a 22-page continuous form banner. Can any other color printer do that?!! I hope HP and Microsoft will remember this wonderful feature. I hate the idea of pulling out Okidatas again just to do Birthday Banners. And in only B&W? As Jack Bruce once sang, "What a bringdown..."