The bulk of the desktop market is enterprise computing, and Google has a lot of work to do if they want to get there. The market wants support, security, and licensing terms that fit their way of doing business. It took Microsoft almost 20 years to significantly displace IBM in this market, and that was with IBM giving them a head start by selling Microsoft's OS with IBM licensing and support.
To some extent, Microsoft has been displaced in overseas desktop and network markets by Linux, by Linux distributors who have learned how to support the enterprise. Here, Google coming in with Android is saying: "hey, switch to Linux with my brand name on it!"
This is not a place where you can give away the software free on the condition that you are permitted to pass through advertising and collect information about everything the computer users are doing.
