Personally, I don’t mind seeing another competitor on the market, it’s well know that this sort of competition makes the end-user happy.
This action is somehow understandable, as I said in other articles, the future of games / content distribution is online (just like Steam) and Google want’s a piece of that big ad-pie that games provide.
Steam has 15 millions user accounts and a traffic of 1.2 millions users per day.