For everyone crying foul, and implying that they can no longer compete with Office 365, it is worth noting a couple of things:
1. This move only affects small businesses. Larger organizations have always had to pay, and private individuals and students remain free (though educational institutions also have to pay - at a reduced rate); and
2. 2013's Office 365 Small Business Premium (which would be the equivalent service from Microsoft) is being sold on a per-user basis, at $150 PER USER PER YEAR (that is 3 times what Google is asking). If you want to Install and manage Office locally and have both local control and 365, the cost is even higher (and MS just raised it by $15 per license per year over last year - see here for pricing details: http://goo.gl/YeHro
). Yes there are discounted packages for large organizations, even then it is still considerably more expensive than what Google is offering (that and that's not the focus of this move, which is directed at small businesses).
BTW, someone please correct me if I'm wrong, but I was under the impression that paid Google Docs accounts (personal, for enterprise or education) did not have adds in them. I thought adds were only present in the free versions and then only when viewed from a desktop/laptop browser. Has that changed?