Look at what happened with Google Maps recently. Was pretty cheap to use, people flocked to it. Then they changed prices. We went from never worrying about paying since we have a relatively small amount of traffic, to scrambling to reduce our usage. Now it is their product, they can do what they want with it, but how many sites are pretty locked into Google Maps?
This seems to be what Google does. They either kill off a free service that people relied on or begin charging lots of money.
Maybe when the "Web 2.0" bubble finally bursts, a key learning for the world will be: you can't build a sustainable business on top of someone else's unsustainable business. If your business depends on a long-term regular supply of anything (information, raw materials, whatever), then you probably want to figure out as quickly as possible how to pay something close to what that is worth and ignore the shifty guys knocking on the back door saying "hey, dude, look at these steaks! best quality! super low prices! don't ask where they come from... I'll even give you the first batch for free!"
Well, in this case it's if you want to use their API to show maps in your application. If you're doing that, you're going to need to pay them in terms of total requests to their backend. Their B2B service and advertising probably funds the normal consumer app (ie just logging onto 'maps.google.com' to find your local coffee shop).
I think they gave us 2 months, which isn't really enough time to adequately look at alternatives given all the other things going on in an organization.
Had we had more time I probably would have looked at doing our own implementation using leaflet and Open Street Map. But that is a pretty big project to throw in when are in the middle of a year long roadmap. I assume this played into Googles strategy. Give them enough of a heads up, but not enough time for most to move away.
I think the service used to only really impact medium-to-big sites, but the price change basically impacts any site. After 25,000 map loads (page hits) you start incurring some substantial fees.
This seems to be what Google does. They either kill off a free service that people relied on or begin charging lots of money.