I randomly googled & opened a 3d printer product, which specified that it supports "Windows XP, Vista, Windows 7, OSX 10.7 beta" (ironically, no Win8)
So, as usual, it means nothing more than empty marketing hype. Windows Vista's "support" for cd/dvd burning meant nothing either. It's not like you couldn't do it before they "supported" it.
It'll mean even less for the common user who'll never use a 3d-printer, and the professional who'll probably never use Win8. (I see large rich client companies being quick to adopt the latest software where managers aren't tech-savvy, but the specialist contractors who sometimes visit to do some consulting work or project are usually still working on Win2000 & Excel with their own modified engineering or finance spreadsheets)
$799 starting price for a 3d printer isn't that bad, i'm sure just like inkjets they will get faster in cheaper in the coming years. I think when you start to see them hit the $399 price point they will really start to take off in the consumer market.
3D support for printing via the OS is a gimmick nothing more. I have a Makerbot replicator 2 and based on the information off MS blog from their so called expert I would never use the OS print feature. It has no support for temperature control, shells, infill and doesn't specify what method it uses to splice the model into layers and print to. Even free third party software like Skienforge has more features. I tried to point this out to the MS blog guy and they censored my post. I wonder why.
In the long run this is the right way to go. Back in the bad old days before unified printer drivers, each piece of software that printed on paper would need to implent their own drivers for each piece of hardware. This meant you tended to be restricted to epson compatible printers and if you where lucky maybe HP compatible ones. Meanwhile the macs had universal printer support from Day #1 so you never had to worry about it (although your choice of printers was limited for other reasons). The implementation of a universal print subsystem in windows changed all that. If the various manufacturers add printer drives for their 3D printers, it means CAD makers just need to work with the API so that eventually ALL printers will work with ALL software. Thats a good thing, people. It just might take some time for all the manufacturers to get on board. Revisit this topic in a year or so and you'll see.