Over at APC, I've outlined five reasons why Chrome OS is a bad idea. The one that perhaps deserves the most prominence is the fact that Linux-based OSes haven't so far managed to attract support from either hardware vendors or buyers:
Even if you don't want to modify the basic system components, you'll probably want to connect your netbook to a USB broadband key or a printer. Getting those vendors on board won't be easy even for Google . . . It's also worth remembering that while netbooks can theoretically run anything, most everyday consumers seem happy for them just to run Windows. ASUS, for example, pioneered the whole market with the Linux-based Eee 701 model, but now only 5% of its models run on Linux.
Competition is good in most any space, but writing a death warrant for Microsoft based on a single blog post seems a little premature, to say the least.