Google launches free beta API: "[Q] Does Google have any plans to sell Google Web APIs as a service? [A] Not at this time."

However, the beta API is limited non-commercial use and to 1,000 requests per day. You have to ask for written consent if you want to build a business on top of their API, so I guess that's when a pricing discussion will occur, on a private case-by-case basis. "What do you plan to do with our API? We see... let's see how much we can charge you for letting you do that."

Update: I might mention that Microsoft released the pricing for its MapPoint.NET web service.