If this question has been answered, I didn't see it. How many different versions of Win7 will there be? So many of the "cool" features of Vista are missing from this Home Premium that I have and I wonder if it will be the same with Win7. We'll be hearing about all the wonderful features for months and months only to find that you need Win7 Ultimate, or whatever they call it, to get all of them.
Regarding articles for 2009, I would do a gut check against the OS market penetration stats from the tracker of your choice. Looking at the Dec 2008 report from Net Applications, XP is around 65%, Vista is up just over 20%, Mac OS is up around 9%, Linux is less than 1%, and Win7 is barely there. Based on that, there will continue to be plenty of audience for XP and Vista even by the time Win7 comes out. Win7 will have to ramp up and who knows where it will steal market share from, but only time will tell.
That this site has more emphasis on Vista than the stats would suggest is probably a reflection of the lack of maturity of the OS. Win7 is getting a lot of posts now because it is exciting and new but hype can only go so far. The trickle of posts in the Mac OS section is probably because there are better forums for Mac devotees. Or, because Macs "just work" so users never need help. :)